Balsamic Roasted Onions
These balsamic roasted onions marinate overnight with brown sugar, rosemary, and spices before roasting with butter until golden and tender. Spoon the reduced balsamic sauce over the onion halves before serving.
Ingredients
Marinade
- 240 ml water
- 240 ml balsamic vinegar
- 2 tablespoons light brown sugar
- 2 teaspoons dried rosemary
- ¼ teaspoon ground black pepper
- ¼ teaspoon red pepper flakes
- ½ teaspoon kosher salt
Onions
- 3 large onions
- 3 tablespoons butter
- 1 teaspoon dried rosemary
Instructions
- Whisk together 240 ml water, 240 ml balsamic vinegar, 2 tablespoons light brown sugar, 2 teaspoons dried rosemary, ¼ teaspoon ground black pepper, ¼ teaspoon red pepper flakes, and 1½ teaspoon kosher salt in a small bowl. Pour the marinade into an 8 x 12-inch baking dish.
- Cut the 3 large onions in half horizontally, leaving the skins attached. Arrange all six halves cut-side down in the balsamic marinade. Cover and refrigerate for 8 hours or overnight.
- Preheat the oven to 400°F (200°C). Turn the onion halves cut-side up. Divide 3 tablespoons butter into 6 equal portions and place on each half, then sprinkle the remaining 1 teaspoon dried rosemary evenly over them.
- Roast uncovered for 1 hour, basting the onions with the pan liquid once or twice, until golden brown and tender. Spoon the reduced balsamic sauce over the onions, remove the outer skins, and serve.
Notes
Plan Ahead: I allow 8 hours for the onions to marinate, so I prepare them the evening before roasting.
Keep the Skins On: Leaving the outer skins attached helps the onion halves retain their shape in the marinade and oven; remove them before eating.
Use a Snug Baking Dish: I arrange all six halves in one layer in an 8 x 12-inch dish so each cut surface sits in the marinade without overlapping.
Baste During Roasting: Spoon the pan liquid over the onions once or twice so the balsamic mixture continues coating them as it reduces.
Nutrition
Calories: 126kcal | Carbohydrates: 17g | Protein: 1g | Fat: 6g | Saturated Fat: 4g | Polyunsaturated Fat: 0.2g | Monounsaturated Fat: 1g | Trans Fat: 0.2g | Cholesterol: 15mg | Sodium: 255mg | Potassium: 139mg | Fiber: 1g | Sugar: 13g | Vitamin A: 203IU | Vitamin C: 4mg | Calcium: 32mg | Iron: 0.5mg
