Roasted red onions are a simple, flavorful side with incredible natural sweetness that pairs beautifully with grilled or roasted meats. Onions usually play a supporting role-here they shine. Roasted until caramelized, then finished with a touch of balsamic and fresh chopped thyme, they deliver rich, savory sweetness. Give this humble ingredient the spotlight it deserves; the depth of flavor will surprise you.
The first time I made these roasted red onions, they turned a beautiful deep brown color, caramelized from the heat of the oven. Roasting turns a normally pungent, eye-watering onion into something rich, jammy, and sweet as candy. I see you looking at me with doubt and skepticism. Trust me. Roast a pan-then try not to eat them straight off the tray.
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Why You'll Love These Roasted Red Onions
- Simplicity - Simple ingredients, straightforward method.
- Big flavor - Deep, sweet-savory caramelization from the oven.
- Veggie boost - An easy way to add more vegetables to the menu.
- Perfect pairing - Lovely with grilled or roasted meats and poultry.
Another terrific recipe with balsamic is these roasted balsamic glaze Brussels sprouts.
Ingredients You'll Need
- Red onions - Any color works, but red roasts up sweet and vibrant.
- Olive oil - Helps caramelize and keep onions tender.
- Granulated garlic - Garlic flavor without burning (fresh scorches).
- Thyme - Fresh chopped leaves for earthy aroma (optional).
- Balsamic vinegar (or glaze) - Finish for tangy-sweet depth.
Please see the recipe card for measurements, salt, and pepper.
If you'd like to make your own Balsamic glaze, it's easy. Find the instructions in this Balsamic strawberries post.
Chef's nutrition tip - Red onions are naturally rich in sulfur-containing compounds - the source of their aroma and many of their health benefits. They're also high in quercetin, a powerful antioxidant and natural antihistamine. A delicious side dish and a nourishing one, too.
How to Make Roasted Red Onions
Pre-heat the oven to 400°F. Ready a large glass or stoneware baking dish, about 10″x13″.
- Step 1: Peel onions and cut in half from the root to stem end. Lay each half flat and cut the halves into 6 wedges.
- Step 2: Add onion wedges to the baking dish and toss with oil, then sprinkle with salt, pepper and garlic.
- Step 3: Roast onions uncovered for about 40 minutes, or until they are very soft and the edges are very brown. Remove dish from the oven, taste for tenderness, then toss with the Balsamic and fresh thyme leaves.
Serving Suggestions
- Serve as a side dish along roast chicken
- Pile on a grilled steak or steak salad
- Pile them on asparagus for a double vegetable side
- Add to a salad, either warm or cold
- Pile on quinoa or rice with other vegetables for a delicious veggie bowl
Recipe FAQs
Similar flavor, different method. Caramelized onions cook low and slow in a pan; roasted onions brown and soften in the oven for a deeper, roasted sweetness and less babysitting.
Roast at 400°F and avoid slices that are too thin. Use a little oil, and line the pan for even browning with parchment and for easier clean up if desired.
Yes - store up to 4 days and reheat gently. Great for meal prep.
You may have sliced the onions too thin, not used enough oil, or roasted too long. Aim for wedges and lightly coat with the oil.
More Onion-Loving Recipes
Onions are the flavor foundation for so many great dishes. Here are a few favorites where they play a starring role. Try one next!
Did You Make These Onions?
If you make roasted red onions, please drop me a comment, I love to hear from you and am always here to help. And if possible, please leave a star rating. Thanks!
📖 Recipe
Roasted Red Onions with Balsamic
Equipment
- glass or ceramic baking casserole dish approximately 10x13
Ingredients
- 2 large red onions about 1 ½ pounds
- 3 tablespoons olive oil
- ½ teaspoon sea salt
- ¼ teaspoon granulated garlic
- ¼ teaspoon ground black pepper
- 1 ½ tablespoons fresh chopped thyme leaves
- 1-2 tablespoons Balsamic vinegar or syrup
Instructions
- Pre-heat the oven to 400°F. Ready a large glass or stoneware baking dish, about 10″x13″. Cut the onions in half from the top to bottom, from root to stem end. Trim the root and stem ends flat. Peel off the papery skin, then lay each half flat on a cutting board and cut the halves into 6 wedges.
- Add onion wedges to the baking dish and toss with oil, then sprinkle with salt, pepper and garlic. Roast onions uncovered for about 40 minutes, or until they are very soft and the edges are very brown. Remove dish from the oven, toss with the Balsamic and sprinkle with thyme leaves. See note below on Balsamic.
Notes
Nutrition
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Porsche Guy says
I made these for serving with a grilled steak and they were great. Really surprised at the sweet flavor. Love Balsamic. Thanks for an unexpected tasty recipe.