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4.1 from 107 votes

Marinated Slow Roasted Onions

These Marinated Slow Roasted Onions get soft and creamy on the inside and caramelize on the outside roasting in a bath of red wine vinegar, brown sugar and spices. Mouthwatering aroma! Best if marinated overnight.
Prep Time5 mins
Cook Time1 hr
Total Time1 hr 5 mins
Course: Side Dish, Vegetable
Cuisine: American, Western
Keyword: marinated onions, Marinated Slow Roasted Onions, roasted onions, slow roasted onions
Servings: 8
Calories: 45kcal
Author: Kevin Is Cooking

Ingredients

Marinade

  • 1 cup water
  • 1 cup red wine vinegar
  • 2 tbsp brown sugar
  • 1 tsp fresh rosemary chopped
  • 1/2 tsp kosher 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.

Notes

1. Trims ends off onions, slice in half horizontally, keeping the skin on to hold shape and protect the outside as it later roasts.

Nutrition

Serving: 1g | Calories: 45kcal | Carbohydrates: 9.4g | Protein: 0.9g | Fat: 0.1g | Sodium: 125.4mg | Fiber: 1.3g | Sugar: 5.4g