Roasted Red Onions with Basil, Fennel Seeds, and Balsamic Glaze
These members of the Allium genus are covered with a red parchment-like skin, and their deep purple and white variegated interior is a glory to behold.
Even raw these onions are on the sweet side, but a long roast in a fast oven transforms them into meltingly soft mouthfuls, dark and sweet as candy. If you are looking for an addition to a platter of mixed vegetables, a topping for a toasty bruschetta or an accompaniment to roasted meats, try these red onions. Their sweetness is heightened by aromatic basil, its hint of licorice a perfect match for the taste and crunch of fennel seeds, blasts of chunky sea salt and the velvety richness of a fine balsamic glaze.
Let your taste be your guide with the basil, lush balsamic syrup, and a glistening sprinkle of coarse sea salt, adding more or less, as you please. Large red onions must be cut into eight pieces each, their woody stem ends cut away; these tough ends will not soften sufficiently during roasting and may pose a choking hazard to diners. Carefully cut away the tough end pieces, taking care to leave enough to hold the onions together. Smaller onions may be cut into quarters or sixths. As good as these onions are tossed with the basil, they get even better with a few dabs of Taleggio or Gorgonzola dolce. The cheeses melt into the onions adding another layer of flavor.
A number of rich balsamic glazes are available now. Trader Joe’s sells a nice one, but look to Acetaia Reale for a uniquely sumptuous indulgence and true balsamic flavor. Acetaia Reale is available from Olio2Go.
Be sure to check fennel seeds for freshness. Spices do not last forever, and if you don’t get a hefty scent of fennel when you open the jar of seeds, it is time to buy new. Fennel is native to the Mediterranean, and is also known as Sweet Cumin. The seeds are available at supermarkets and at many specialty spice purveyors, such as Penzeys Spices and Savory Spice Shop, both online and at each company’s brick and mortar stores.
Roasted Red Onions with Basil, Fennel Seeds, and Balsamic Glaze
The onions may be served right from the oven, warm or at room temperature. Topped with cheese, they are best served warm.
2 pounds red onions
½ cup extra virgin olive oil
1 ½ teaspoons fennel seeds
1 tablespoon coarse crystal sea salt
½ cup whole basil leaves, whole or cut in chiffonade
Acetaia Reale Balsamic Glaze, as desired
Optional Gorgonzola dolce or Taleggio
Preheat the oven to 400 degrees F. Cut the red onions into eighths if large, sixths, or quarters if small. Toss very gently to coat with olive oil. Place the onions in a 9X9 ovenproof dish, and sprinkle with the fennel seeds. Place the baking dish on the middle rack of the oven and roast for 1 hour to 1 hour and 10 minutes, until the onions have softened and caramelized.
Remove the onions from the oven, and spoon some of the oil from the baking dish over them to coat. Drizzle with Acetaia Reale Balsamic Glaze, and sprinkle with coarse sea salt. Tuck whole basil leaves among the onions or top with cut basil and serve.
If the onions are to be served with the optional cheese, dab chunks of either Gorgonzola dolce or Taleggio atop the onions while still quite warm and serve immediately.
Adapted from Nigellissima by Nigella Lawson
Acetaia Reale Balsamic Glaze is available from Olio2Go.
Note: You can click on any picture and see a slide show!
I have no affiliation with any product, manufacturer, or site mentioned in this article.
Photo of Acetaia Reale Balsamic Glaze courtesy Olio2Go
Saturday, May 3rd 2014 at 1:10 am |
che bel modo per gustare le cipolle, molto saporito ! Buon weekend cara Adri, un abbraccio !
Saturday, May 3rd 2014 at 6:01 am |
Ciaa Chiara,
Grazie! E buon weekend a te!
Saturday, May 3rd 2014 at 6:38 am |
I’m in Adri. I saw this recipe on Facebook and was immediately drawn in. I am waiting impatiently for all the produce at the farmers market.
Saturday, May 3rd 2014 at 6:55 am |
Hi Val,
These are sweet as candy. The recipe is very simple, and served hot or cold, these really are great. Have a wonderful weekend!
Saturday, May 3rd 2014 at 9:05 am |
Simplicity at its best! Those purple onions look very delicious.
Saturday, May 3rd 2014 at 1:06 pm |
Ciao, Angie,
Simple is right! These are one of my new faves. Have a great weekend, and thanks for stopping by.
Saturday, May 3rd 2014 at 9:33 am |
Wow! Beautiful as usual and this one (and the last post too) look like something even people who are hopeless in the kitchen might be able to do. I am going to try them both — they also look so classy that I might be able to fool someone into thinking I am a decent cook. Thanks for sharing your secrets. Ciao, Trisha
Saturday, May 3rd 2014 at 1:09 pm |
Ciao Trisha,
Thanks-you can definitely do these. They are simple, and the very definition of something that is more than the sum of its parts. The onions are especially surprising. Hot directly from the oven, warm or with a chill on them, they really are fab. Thanks for stopping by and for the kind words. Un abbraccio forte!
Saturday, May 3rd 2014 at 9:39 am |
Red onions don’t get enough love. Their flavor is extraordinary, IMO, and their color is totally gorgeous. And this dish sounds wonderful! What a delightful combo of flavors. And my basil plants will soon be mature enough so I can start harvesting them. Definitely should try this — thanks.
Saturday, May 3rd 2014 at 1:11 pm |
Hi John,
You are so right about red onions. I have taken to using them a lot over the last year, and I have developed a rel appreciation for them. This dish is great summertime fare. Have a fab weekend, and thanks for stopping by.
Saturday, May 3rd 2014 at 11:27 am |
I’ve never tried roasting red onions before – wonderful idea! They look delicious.
Saturday, May 3rd 2014 at 1:15 pm |
Hi Susan,
Red onions develop such nice flavor when exposed to some serious oven heat. I used to use them only in their uncooked state, in salads and as condiments, but roasting amplifies their flavor and enhances their innate sweetness. I bet you will enjoy this preparation. I hope you are having a nice restful weekend!
Saturday, May 3rd 2014 at 1:04 pm |
Red onions are my favorite! I always add them when roasting a variety of vegetables. I\’d be in heaven with a batch of your balsamic glazed onions…they look divine!!!
Saturday, May 3rd 2014 at 1:21 pm |
Hi Liz,
I have really gotten to be a big fan of red onions over the last year or so. They are gorgeous and have such a depth of flavor. I bet you will enjoy this one. Have a wonderful weekend!
Saturday, May 3rd 2014 at 2:33 pm |
Great recipe Adri. I love red onions, they are so tasty and healthy. I also eat them raw in my salad. Un abbraccio, Paola
Saturday, May 3rd 2014 at 2:55 pm |
Ciao Paola,
I love them too. With their mild and sweet flavor profile, red onions are a natural in salads, especially with citrus. At first I thought the roasted onions were best only for the winter months – with roasted meats. However, I tried some of the onions atop bruschetta with bits of Taleggio and I realized just how versatile this preparation really is. I bet you will find a million ways to enjoy it. Thanks for stopping by – un bacione a te!
Saturday, May 3rd 2014 at 3:17 pm |
I’ve roasted red onions with balsamic, but the addition of fennel seeds in an inspiration. GREG
Saturday, May 3rd 2014 at 4:45 pm |
Ciao Greg,
I love the play of the syrupy rich balsamic glaze and the caramelized onions, but I have to say that the fennel seeds put this one over the top. I hope you try it; I would love to hear your thoughts. It is already hot here, and so the idea of oven roasting is rapidly beginning to lose its appeal, however the good news is that these do very nicely in a covered outdoor grill or wood burning oven. Have a great weekend!
Saturday, May 3rd 2014 at 7:46 pm |
Fennel seeds are the building blocks of most of my family heritage recipes, they were added to so many foods, i go thru them like candy..and eat them Like candy too! Love the whole recipe Adri! Che Buona!
Saturday, May 3rd 2014 at 8:07 pm |
Ciao Peter,
I love fennel seeds too, and they are so good here. I’m glad you like this one. Buon weekend!
Saturday, May 3rd 2014 at 7:58 pm |
I always learn so much about food and cooking from you! I am a huge fan of fennel seed but never would have thought of this combination. Delish! What is gorgonzola dolce? It sounds like sweet cheese?? YUM!
Saturday, May 3rd 2014 at 8:23 pm |
Hi Pam,
Thank you! I am so pleased to hear that your time here is well spent. Gorgonzola dolce is also known as Sweet Gorgonzola. This young cheese is quite creamy and somewhat sweet when compared to the other main variety of Gorgonzola known as Mountain Gorgonzola or Gorgonzola Piccante. This second variety is aged longer than the dolce variety and so it is firmer and somewhat less creamy, a bit drier with a prized, thick rind. Both cheeses, however are made of cow’s milk and are specialties of the northern regions of Italy. Next time you are at the cheese monger’s, ask for a side by side tasting of the two varieties, and I bet the differences will be readily apparent. Thanks for stopping by!
Sunday, May 4th 2014 at 6:49 am |
Sounds and looks delicious! Touch of balsamic…mhh, delicious! 🙂 ela
Sunday, May 4th 2014 at 9:29 am |
Hi Elzbieta,
Thank you! I just love the balsamic glaze. I hope you try this one, and have a wonderful day!
Sunday, May 4th 2014 at 11:59 am |
oh my word! I have no words. I mean really? I love love onions roasted and the idea of pairing the with the sweet fennel and balsamic is insanely genius and so delicious!
Sunday, May 4th 2014 at 1:03 pm |
Greetings!
I am so glad you like this one. I just flipped for the flavor combo. I hope you try it, and I would love to hear what you think. Have a wonderful afternoon, and thank you so much for stopping by.
Sunday, May 4th 2014 at 12:21 pm |
These are indeed hard to resist Adri. I’ve roasted yellow onions in this manner before, with the balsamic, but never the fennel seeds. I’ll bet the red ones are even more like candy – if only we could get those red onions from Tropea here!
Sunday, May 4th 2014 at 1:11 pm |
Ciao Linda,
Oh, tell me about those Tropea Rossa onions. We really ought to get some seeds from Seeds from Italy and grow our own because I think you are right about how good they would be here. I forgot to mention it, but these were also fab over farro with lots of basil tucked in and some Gorgonzola dolce. They are so sweet and luscious, I think I may just start calling these “Candied Onions.” Thanks for stopping by and for the kind words. Have a great afternoon.
Sunday, May 4th 2014 at 12:36 pm |
We grow 4 different kinds of onions, plus leeks and shallots, so this recipe will fit in very well around here. I cannot wait to try this wonderful combination of flavors! Thanks, Adri!
Sunday, May 4th 2014 at 1:21 pm |
Hi Donalyn,
This one was my pleasure entirely. You have a regular Creekside Onion Farm going on, and I am having some serious Allium envy over here! This is my first year growing any member of this particular family. I planted a variety called Cipolla Pompei Bianco, a small bulb onion that is a bit like scallions, but with slightly larger, rounder white bulbs. I am looking forward to my harvest. I hope you try these, and I would love to hear what you think. Thanks for stopping by. Alla prossima!
Sunday, May 4th 2014 at 12:57 pm |
Adri, this is a fabulous approach to red onions and I would so want to add in the gorgonzola. I’m thinking of this with a nice steak.
Sunday, May 4th 2014 at 1:29 pm |
Ciao Angela.
You’ve got the idea-a steak would be perfect. Add the Gorgonzola dolce and prepare to enter culinary heaven. In fact with a nice grain – say some farro to soak up the sauce, you’d have a wonderful meal. The onions cook up like candy, so sweet and soft. Who knew that the humble onion could be so transformed? Thanks for stopping by, and I hope you enjoy the onions. Alla prossima!
Sunday, May 4th 2014 at 7:38 pm |
Hi Adri, thanks for dropping by, and leaving such a heart warming comment. I love red onions, and often use them in salad form to accompany meat/fish dishes. Tomorrow I am planing some fish for dinner, and this is just in time. I am so going to try this. fennel and balsamic, how inventive!
Monday, May 5th 2014 at 8:34 am |
Hi Minnie,
Thank you for visiting! I hope you enjoy this one; the taste of the fennel and balsamic marry beautifully with the roasted onions. Have a wonderful week!
Sunday, May 4th 2014 at 9:25 pm |
I love your roasted onion dish and it does sound amazing with the fennel seeds and the balsamic glaze. I love taleggio cheese so I would definitely buy that to have with the onions xx
Monday, May 5th 2014 at 8:35 am |
Welcome!
I am glad this one caught your eye, and the Taleggio is a wonderful accompaniment. Enjoy, and thank you for visiting!
Monday, May 5th 2014 at 1:54 pm |
What great flavors! The balsamic glaze sounds delicious.
Monday, May 5th 2014 at 10:07 pm |
Hi Lisa,
These are tasty indeed. I hope you give them a try, and thank you for stopping by.
Tuesday, May 6th 2014 at 6:07 pm |
It’s hard to imagine anything more luscious than those photos, but then your prose are the real food porn! Incredible; onion candy is the perfect way to describe it.
Tuesday, May 6th 2014 at 9:19 pm |
Hi Hannah,
Candy was just the best way to describe them. We could not stop eating them! Thanks for the kind comment!
Tuesday, May 6th 2014 at 11:14 pm |
Onions and balsamico make the perfect match!
Wednesday, May 7th 2014 at 6:08 am |
Hi Katerina,
They certainly do. The extraordinary caramel notes of both marry so beautifully. Thank you for stopping by.
Wednesday, May 7th 2014 at 2:33 pm |
Seriously Adri, I would eat these with just about anything! And they\’re soooo easy!
Thursday, May 8th 2014 at 6:39 am |
Hi Laney,
Thanks! They are a great flavor combination, and the fennel really sets this one off.
Wednesday, May 7th 2014 at 6:12 pm |
I love red onions with balsamic. I had not thought to use fennel, but now I will.
Madonna
MakeMineLemon
Thursday, May 8th 2014 at 6:40 am |
Ciao Madonna,
I think you will enjoy the fennel, and the balsamic glaze lends a particularly flavorful touch. Thanks for stopping by!
Wednesday, May 7th 2014 at 8:58 pm |
I adore onions. This looks so good!
Thursday, May 8th 2014 at 6:41 am |
Greetings!
I hope you give this one a try. It is simply recipe, and really tasty.
Thursday, May 8th 2014 at 3:40 am |
Onions and balsamic are a match made in heaven and fennel always brings an incredible amount of flavor. Lovely dish.
Sam
Thursday, May 8th 2014 at 6:42 am |
Hi Sam,
You are so right. I particularly enjoyed the ultra-rich balsamic glaze here. We ate them like candy!
Saturday, May 10th 2014 at 5:14 am |
I enjoy roasted onions but I don’t know why I’ve never thought to use red onions. Love your addition of basil and fennel.
Saturday, May 10th 2014 at 7:19 am |
Hi Karen,
The red onions are sweet to start, and like you, I wonder why I never tried this before. They really do become almost candy like, and the balsamic syrup is the proverbial icing on the cake. Have a great weekend!
Saturday, May 10th 2014 at 5:27 am |
Hi Adri, roasting those reds brings out that candy-caramel sweetness, so good. I love the addition of fennel seeds to this dish—inspiration! many thanks
Saturday, May 10th 2014 at 7:21 am |
Hi Nancy,
This one is my pleasure – start to finish. I hope you try this preparation. Hot or cold, these onions really are sumptuous. Have a great weekend!
Saturday, May 10th 2014 at 5:33 am |
This really sounds amazing. I love the intense flavor of roasted onions and I can see how balsamic vinegar would send it over the top.
Saturday, May 10th 2014 at 7:23 am |
Hi Frank,
Intense is the word, and somehow the red onions were even sweeter than I had expected. The onions, fennel, basil and balsamic are more than the sum of their parts. I bet you’d love this one. Buon weekend a te!
Saturday, May 10th 2014 at 8:46 am |
Ooohhhh, you have my mouth watering with this beautiful dish, Adri. This will be perfect with grilled meats that we love to cook on the grill in the summer. Slow roasting does bring out the sweetness in red onions and a balsamic glaze is the perfect finish. Thanks for the reminder to check dates on spices. I know I have a few ancient ones in my cupboard.
Saturday, May 10th 2014 at 9:36 am |
Hi Cathy,
About those ancient spices, try as I may I find things that are three and four years old when I go through my pantry. I open them up and they smell of nothing so much as dried grass. I think I ought to use some of my spice more often! I hope you try these onions. You are right on the money; they will be fab for summer grilling fests, and you can do them in a covered grill. That’s the real good news!
Sunday, May 11th 2014 at 7:11 am |
HI ADri! We’ve heard about roasting fennel and onions for years now, and never ever made them yet, but now you have inspired us to try and use your recipe ( since we don’t have one). Grazie!
Have a wonderful day!!
Sunday, May 11th 2014 at 12:35 pm |
Ciao sorelle!
I am glad to be of service, and I really hope you try these. The Italian garden offers many variants of the red onion, and I bet you will enjoy fiddling around with this preparation and making it your own. Thank you for stopping by and buon domenica!