Marinated Slow Roasted Onions

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!

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.

4.03 from 249 votes

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Course: Side Dish, Vegetable

Cuisine: American, Western

Keyword: marinated onions, Marinated Slow Roasted Onions, roasted onions, slow roasted onions

Prep Time: 5 minutes

Cook Time: 1 hour

Total Time: 1 hour 5 minutes

Servings: 8

Calories: 90kcal

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 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

1. Trims ends off onions, slice in half horizontally, keeping the skin on to hold shape and protect the outside as it later roasts.
2. 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

Serving: 1g | Calories: 90kcal | Carbohydrates: 8g | Protein: 1g | Fat: 6g | Saturated Fat: 4g | Cholesterol: 15mg | Sodium: 203mg | Potassium: 92mg | Fiber: 1g | Sugar: 5g | Vitamin A: 177IU | Vitamin C: 4mg | Calcium: 19mg | Iron: 1mg

Have you made this recipe? Let me know on InstagramTag @KevinIsCooking and hashtag me #keviniscooking!