These Marinated Slow Roasted Onions are a side dish that are worth you taking a look at. Really. Not your typical side dish like a green bean casserole or a baked potato, these onions caramelize roasting in a bath of red wine vinegar, brown sugar and spices.
The result is a soft and creamy on the inside and caramelized on the outside onion that mellows in flavor and takes on the marinade to make a memorable side on the holiday table.
Roasted onions you say? Why yes, these Marinated Slow Roasted Onions are incredibly delicious and so easy to make and the aroma will get your mouth watering. I wanted to share with you a quick and tasty side dish today with all the upcoming holidays.
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.
Trimmed onions get sliced in half horizontally, keeping the skin on to hold shape and protect the outside as it later roasts. Then marinade overnight, dab with some butter, chopped rosemary and slow roast in the marinade. Heavenly!
This one you need to plan ahead for as the onions marinate overnight before roasting. While you’re at it these Herb Roasted Poupon Potatoes could easily be made at the same time!
I’ve made them without marinating and feel the overnight soak really makes this rich and flavorful. I occasionally add fresh chopped rosemary at the last 5 minutes of roasting for an added punch of flavor. Enjoy!
This recipe first appeared on Kevin Is Cooking November 2017 and has been updated with a new video.
Watch how to make this below!
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Marinated Slow Roasted Onions
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
- pinch red pepper flakes optional
- 4 large white or yellow 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 8x8" 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 wide 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 (See Note 2).
Notes
- Trims ends off onions, slice in half horizontally, keeping the skin on to hold shape and protect the outside as it later roasts.
- I keep the skin on to hold the onion in one piece while roasting, just discard the pouter, dried skin before eating.
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
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.
About to do this onion dish
How did it turn out?
Hi, do you think red onions would work?
If you try them let me know how they turn out! I would love to hear!
hello keven can these be froen after roasting as i am only one that really likes onions thank you
I have never frozen these to give an answer, but I would just make a smaller batch myself and roast. If oy udo freeze them, please let me know how thay are. I’m sure the texture will be quite different. Cheers!
Hi Kevin, these onions sound awesome,and I can’t wait to make them,I’ll definitely be adding the garlic as mentioned below.
I am so glad you enjoyed them! We love the around our house!