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 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!
- Marinade:
- 1 cup water
- 1 cup red wine vinegar
- 2 tbs brown sugar
- 1 tsp fresh rosemary chopped
- 1/2 tsp kosher salt
- 1/4 tsp black pepper
- pinch red pepper flakes optional
- 4 large onions See Note1
- 4 tbsp butter
- 1 tsp fresh rosemary chopped
- 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 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 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 from skins and serve.
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I am definitely going to save this recipe to make over the weekend. I have a beautiful roast they would be perfect to serve with!
Stunning pictures too
Thanks so much Brynn! I hope you’ll enjoy them. 🙂
These are stunning! Love the pictures! They are making me drool!
Thanks Zerrin, they actually taste as good as they look, too! Have a wonderful weekend. 🙂
What a lovely idea, these sound so delicious. A great recipe for autumn!
Thanks Caroline, they really are pretty amazing as a side dish. Cheers!
You are totally speaking my language with these onions Kevin! I think I could eat the whole entire pan! No shame. Perfect with a nice juicy steak! Happy weekend!
You’re going to love the aroma and they taste even better! Thanks Mary Ann.
Kevin! I can’t even with this! I want to swim in that pan! I am a huge fan of onions. A huge fan of anything roasted. And a huge fan of all that you produce. Oh. My. God. That’s all.
Thanks Annie, you are one of my reader and fellow food blogger friends that always puts a smile on my face! 🙂
Hey Kevin! We eat tons of onions and these will be on the table soon! These would be lovely as a side with Nagi’s leg of lamb she posted today! Can I include this in the “holiday” fare?
By all means include! Thanks Dorothy 🙂
They look great. Can’t wait to try. One question, your pictures show a pat of what looks like butter on each onion half but it isn’t in the recipe. I do think everything (at least most things) are better with butter so I thought I would ask. Should butter be in the recipe?
I couldn’t agree more David! Updated to reflect, thanks for the eagle eye my friend! Hope you enjoy these.
Oh my! These are beautiful!! I can think of so many upcoming get togethers where these onions will impress…and vanish, but I also see these in my weekly menus, the overnight marinade sounds incredible and easy. Rosemary is one of my absolute favorite herbs, too. Two thumbs up!
Thanks so much Sally, they’re a house favorite too. Just make sure, due to different sizes of onions, that they are tender as times may vary. 🙂
What a delicious idea! I’ve never done marinated onions on the stovetop like this, but we love brushing thick-cut onions with herbs and olive oil and then tossing them on the grill. This sounds like the winter version of that one…and I definitely need this to happen soon! Love it!
Awesome to hear, these are a fantastic side whether it’s a holiday dinner or not Dave. That vinegar mellows as do the onions slow roasting like that, but the flavor combo is wonderful.
I’ve made roasted onions before, but these look SO much better! I can tell you one thing’s for sure….these are in my future. Can’t wait to try and love how all the onion layers opened up a bit. Onions are complex like that, lots of layers to their personality, lol 😉 And you know I’m all over this recipe ’cause of the vinegar. The rosemary at the end is a nice touch and pop of colour too. Pinning!
Thanks Dawn, these get almost creamy inside, but hold their shape. I love the roasted edges and the surprising flavor from the vinegar is awesome. 🙂