Marinated Roasted Onions
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These slow roasted onions are 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.
Roasted 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.
Marinated Roasted Onions
Ingredients
Marinade
- 1 cup water
- 1 cup red wine vinegar
- 2 tbsp brown sugar
- 2 tsp fresh rosemary chopped
- 1/2 tsp kosher 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 and tender, 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.
Video
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.
Nutrition
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.
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!
Hi Kevin – I’ve prepped the onions and am excited to try your recepie! Does roasting the onions emit the vinegar odor? Wanted to get your on cooking this in a slow cooker so I can pug it in and cook it outside… if it’s possible, how long would you recommend in a slow cooker? Could i broil it in the oven to crisp them up?
Sorry for the late reply Wendy, I just found this in my Spam folder. How did they turn out?
I’ve made this recipe HEAPS of times now and always tell my friends to try it as well. Its super easy, fabulous because you can do almost everything the night before and it tastes great. A real winner
I am so glad you have made it more than once! Thank you!
I saw this and omg, im thrilled. I just got it all ready in my 8×8 pan and just put in my frig for over night. I hope it turns out good. I used the same recipe that it called for. I love onions but the wife hates them, but little does she know ive been adding them in meals. She dont even know. Onions do make good tastey food. Brings alot of flavor. Cant wait to eat them tomorrow with my steak.😉
We love them Jamie! Gotta sneak them in sometimes! How did they turn out with your steak?
Wonder about putting a tablespoon or so of bourbon in the marinade as well – good with steaks? I’m going to try this over the coming weekend.
Let me know how it turns out!
Would you have a video of these carmalized onions
Michelle, yes! It’s right above the recipe card on the post. Enjoy!
What happens to the skin after it’s baked? Does it need to be removed in order to eat the onions?
I keep the skin on to hold the onion in one piece while roasting, just discard the pouter, dried skin before eating.
I tried this and they tasted delicious. One question… should the onions still be crisp/crunchy? I cooked for one hour at 400. Should I cook for longer to achieve the soft/creamy onion? Thanks
They should be a little firm, but not crunchy. We want that melt in your mouth feel. It’s the main reason I keep the outer skin on to hold them together while cooking. I guess it does depend on the onion/variables in size. Cook to your liking, but favor the softer side. Cheers Nicole!
These look delicious 😋will definitely make them!
So glad! Let me know how they turn out!
How do you calculate the nutrition? In just the butter alone (1/2 tbsp) you would have 6 g fat and 51 cal.
Most food blogs, as does mine, use a plugin that calculates the nutritional information based on ingredients and number of servings. Hope this helps Warren!
One quick question. I don’t have red wine vinegar. I only have Chinese red vinegar or apple cider vinegar. Do you think either one would work?
My choice would be to use the apple cider vinegar Pam. Hope you enjoy!
Thank you.