Marinated Roasted Onions
A sweet and savory side dish that transforms humble onions into a comforting and indulgent treat that pairs perfectly with various mains.
Ingredients
Onions
- 6 medium medium onions (yellow or sweet) Halved lengthwise for large wedges or peeled and left whole for small shallots.
Marinade
- 3 tablespoons olive oil Substitute avocado oil for a neutral flavor.
- 2 tablespoons balsamic vinegar Adds sweet acidity; maple syrup can be used for a different sweetness profile.
- 1 tablespoon red wine vinegar Brightens flavors; lemon juice works if you prefer citrus.
- 2 teaspoons kosher salt Balances and draws out sweetness.
- 1 teaspoon black pepper Freshly ground for the best aroma.
- 2 cloves garlic Smashed; or 1 teaspoon garlic powder if you need a quick swap.
- 1 tablespoon Dijon mustard Gives body to the marinade; use whole-grain mustard for texture.
- 1 tablespoon honey or maple syrup Optional, for added glaze and depth.
- Fresh thyme or rosemary sprigs Fragrant and festive; parsley works as a fresh garnish.
- Optional: a splash of sherry or white wine For an adult-friendly nuance.
Instructions
Preparation
- Preheat your oven to 400°F (200°C). Line a baking sheet with parchment for easy cleanup.
- Make the marinade: whisk together olive oil, balsamic vinegar, red wine vinegar, Dijon mustard, honey (or maple), salt, pepper, and smashed garlic in a bowl. Taste and adjust, keeping in mind roasting will deepen the flavors.
- Toss the onions: Place the halved onions in a large bowl, pour the marinade over them, and gently toss to coat each piece. Let sit for 5–10 minutes if you have time—this is when the flavors begin to sink in.
Roasting
- Arrange onions cut-side down on the baking sheet with sprigs of thyme or rosemary tucked around them. Roast for 20–30 minutes until edges are caramelized and centers are tender. Smaller onions may take less time.
- Flip the onions gently and roast another 10–15 minutes until deeply golden. Your kitchen will smell amazing at this point—sweet, tangy, and comforting.
- Transfer roasted onions to a shallow dish, pour any drippings back over them, and let cool slightly. For true marinated flavor, cover and refrigerate for at least 30 minutes or overnight; serve at room temperature for the best texture.
Notes
For a festive meal, add toasted pine nuts and chopped dried cranberries before serving. Make it smoky: add smoked paprika or roast over coals for outdoor flavor. To reheat, warm in an oven for 10–15 minutes or on the stovetop with a splash of water to loosen the glaze.