This baked onion side dish is easy to make for a simple, flavorful holiday side. Make this recipe to serve with your holiday ham, turkey, or beef roast.
This recipe is worth you taking a look at. Really. It’s not a typical holiday side dish like traditional French’s green bean casserole or roasted potatoes, but I bet you’ll love it just as much. The onions caramelize roasting in a bath of red wine vinegar, brown sugar and spices.
The result is a tender vegetable that’s soft and creamy on the inside and caramelized on the outside. The flavor is mellow and sweet, and it takes on the flavor of the marinade, making a memorable side on your holiday table.
These make it to our table more times than I can count because they don’t need a holiday reason to sing and are perfect with grilled meats when no holiday is the reason.
Baked Onion – Choosing the Right Variety
- Best Onions for Roasting / Baking
Because this is a side dish recipe, the best option is to use an extra large variety of onion. You’ll be slicing them in half and leaving the skins on while they bake, so I recommend using a large, sweet variety like Vidalia or yellow. You could even use red onion, which also tastes fantastic caramelized!
- Choosing a variety based on the protein you’re serving.
- Poultry– If you’ll be serving the roasted onions with a roast turkey, I think yellow is your best option.
- Pork– The best option to serve with a holiday ham is definitely Vidalias. Their sweetness pairs perfectly with glazed ham, especially if you’ll be using a slightly spicy glaze like chipotle orange.
- Beef or Lamb– For boneless prime rib, lamb roast, or braised beef brisket, any type of onion works well. This is where making baked roasted red onions might be a great choice.
Video: Making Marinated Roasted Onions
The recipe is pretty simple and aside from the marinating, it’s really quick and easy to make. Watch the video in the recipe card to see the process from start to finish.
Planning Ahead
This roasted onions recipe is one you need to plan ahead for, as the onions need to sit and marinate overnight before roasting. While you’re at it, these Herb Roasted Potatoes could easily be made at the same time!
NOTE:
I’ve roasted onions without marinating, and they’re okay. But I feel the overnight soak really makes a difference. If you’re crunched for time and need to skip the overnight soak, at least let them marinate for an hour if you’re able to.
This is a rich and flavorful side dish, and it really does go well with nearly every protein you can think of. For a nice garnish and punch of flavor, I occasionally add fresh chopped rosemary during the last 5 minutes of baking time.
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This post, first published on Kevin Is Cooking November 2017, was last updated with new content on Sept. 11, 2021.
Slow Roasted Baked Onions + Video
Ingredients
Marinade
- 1 cup water
- 1 cup red wine vinegar
- 2 tbsp brown sugar
- 1 tsp fresh rosemary chopped
- 1/2 tsp salt
- 1/4 tsp black pepper
- 1 pinch red pepper flakes optional
- 4 large onions (See Note 1)
Roasting
- 4 tbsp butter
- 1 tsp fresh rosemary chopped
Instructions
- Blend marinade ingredients in small bowl and pour into a baking dish that will hold all 8 onion halves. I use 8×8″ baking pan or round 12″ baking stone (pictured) depending on size of onion.
- Trim the end of onions and cut horizontal (leaving skin on) and place cut side down in marinade. Marinate overnight covered in refrigerator.
- Preheat oven to 400°F. Flip the onions over in the marinade, and lay on the flat bottom of each side. Top each onion with 1/2 tablespoon of butter and remaining teaspoon of rosemary.
- Roast uncovered in oven for 1 hour or until golden brown, basting once or twice during roasting. Remove from heat, spoon reduced sauce over and sprinkle with parsley or more fresh chopped rosemary. Remove outer skins before eating and serve.
Notes
- White, yellow, or red onion may be used. Trim ends off onions, slice in half horizontally, keeping the skin on to hold shape and protect the outside as it roasts. Just peel and discard the skins before serving.
The information shown is an estimate provided by an online nutrition calculator. It should not be considered a substitute for a professional nutritionist’s advice.
Nutrition
Hi! I’ve been making these on and off for the last 5 years. Everyone loves them, I love them. They are easy enough for weeknights and elegant enough for company and holidays. That little pat of butter makes a world of difference! This is a really great recipe!!!! Thanks Kevin…. P.S. I absolutely appreciate the calorie count on your recipes. It makes my life so much easier (and tastier!)
Sl glad these are a hit and thanks for taking the time to come back and let me know Mary.
I wasn’t sure what to expect since I’m not a huge vinegar (or onion) fan. I had a lot of onions to use up and found your recipe on Pinterest. I’m so glad I did! I’d read your recipe, but when I went to go prepare the marinade, I could pull it up due to an issue with my phone, but it’s so easy I’d gotten most of it right. When I tasted it, I’d oversalted, so I evened out with a little more brown sugar until it seemed balanced. At any rate, end result – delicious! Such an easy… Read more »
Fantastic! So happy you enjoyed this one and went for it Johna!
Ill be trying this, but with beef stock instead of wine. (I may be the only person on earth that hates wine, even in cooking.)
There is no wine (alcohol) in this recipe, it’s red wine vinegar. The flavor of the onions will still be delicious if you omit, and I hope you try them!
There’s not any wine in this recipe
I was wanting to watch the video but I can’t find it anywhere.
The video is in the recipe card after the Ingredients and before the Instructions Linda. Do you have an ad blocker on your browser? That could be what blocking it. Also, I have a Youtube channel where all my videos are if you’d like to see them anytime: https://www.youtube.com/c/KevinIsCooking
These onions look awesome! Will have to make them soon!
i WANTED TO MAKE THIS FOR A PROGRESSIVE DINNER PARTY. MY STOP IS SECOND AND SERVED OUTSIDE. WONDERED IF THEY COULD BE SERVED ROOM TEMPERATURE? WOULD BE 6 HOURS AFTER BAKING. BY THE WAY LOVE YOUR SITE.
Certainly, and I have even had them cold the next day. It’s up to you. Have a wonderful, safe and delicious Thanksgiving Mary!
thank you! I can’
t wait to try them. they are such a beautiful presentation.
So I made this recipe last night and I did it a little different cause my onions were missing the skin. I wrapped it with foil (to act like the skin) and it came out delicious. Also, I added thyme, garlic, and coriander to the marinade. I had this with pork meatballs, arugula salad and toast. This is a keeper!!
So glad you enjoyed these Lani!
I decided to try them only by seeing those wonderful gorgeous photos! Let’s see how this comes out with Indian version.
Love your thinking Deeksha! By the way, have you seen my other food site Silk Road Recipes, lots of tasty foods there from the Mediterranean East to China!
Really excited to try this recipe out! Got everything from the store (I thought at least…) then discovered I don’t have any red wine vinegar. Would Balsamic be an ok substitute?
You can substitute with that but the flavors will be different. Let me know what you decide!
Sounds good to me! Will try at on the weekend.
Excellent Keira! These are so good!
I made these today to put on toast with ricotta and roasted cherry tomatoes. TO DIE FOR. No one spoke a word until the last bite was had!
I am so glad Alex! Thank you for sharing this!
I thought I’d done this recipe about six months ago but instead of water and red wine vinegar it was chicken broth and Cabernet Sauvignon. It was really good.
I hope you enjoyed this one!