An easy recipe for roasted red onions. Baking them in the oven removes any sharpness, so the onions are mellow and creamy.
They're great as a side dish, in a salad, or as a topping for hamburgers and steaks.
We don't usually think about onions as a side dish. We mostly use them as a condiment, as a way to season our food. So we chop them up and add them to salads, chilis, and other recipes.
But onions can actually serve as a great side dish. Roasted onions are wonderful, for example. Pickled red onions are good too, although that's indeed more of a condiment.
These roasted red onions are wonderfully mellow and creamy. It's like magic! Roasting takes the onions from bitter and pungent to mild and caramelized, almost sweet.
The same thing happens when roasting garlic. The sharpness is replaced with wonderful creaminess. In both cases - onions and garlic - I'm not a fan of the raw vegetable. But the cooked version is absolutely delicious!
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Ingredients
You only need three simple ingredients to make this recipe. The exact measurements are listed in the recipe card below. Here's an overview of what you'll need:
Red onion: I haven't tried making this recipe with white or yellow onions. You can try using yellow onions. But the white ones are quite sharp - I don't know if they're good candidates for this recipe.
Olive oil: This is my favorite oil and I love cooking with it. But if you're unsure about cooking with it, you can use avocado oil instead. It has a higher smoke point. Another tasty option is using melted butter.
Kosher salt: If using fine salt, you might want to reduce the amount you use or the dish could end up too salty.
Instructions
Roasting red onions is easy! Scroll down to the recipe card for detailed instructions. Here are the basic steps:
- Peel the onion, slice it into slices, and separate the slices into rings. The video below shows you how I do it.
- Now, spread the onion rings in a baking dish. Toss them with some olive oil and sprinkle them with kosher salt.
- Roast them at 400°F until soft and caramelized, about 20 minutes. That's it! Super easy. And so tasty!
Expert tip
How do you slice an onion? You wash, dry, and peel it. Then slice it into ¼-inch thick slices and separate the slices into rings. You can also cut them into quarters if you prefer and roast them for a little longer.
Frequently asked questions
Yes. High heat roasting as we do here caramelizes the onions. To promote caramelizing, you can also add a bit of balsamic vinegar - about ½ tablespoon. The sugar in the aged vinegar will help the onions caramelize.
It's really a matter of personal preference. Their sharpness is good in salads, as long as you slice them very thinly or mince them. I like them eaw in an Israeli salad, for example.
When cooked, they mellow out and provide a completely different experience. Instead of sharpness, they provide an umami-type flavor (savoriness).
Yes. You can use this recipe for sauteed onions. I typically use yellow onions, but it will work with red onions too.
Variations
One way to vary this recipe is to use butter instead of olive oil. Another variation, mentioned above, is to add ½ tablespoon of aged balsamic vinegar. This will add flavor and promote caramelizing.
Serving suggestions
These onions make a delightful side to any meat dish, especially to grilled meats. I often serve them with grilled chicken tenders.
They are also excellent with baked chicken thighs, and I love being able to roast both dishes in the same oven. Needless to say, they make a great topping for hamburgers!
Storing leftovers
You can keep the leftovers in the fridge, in a sealed container, for 3-4 days. They can be reheated in the microwave, and they taste great - just as good as fresh. I also like to add them the next day to an omelet, or even (cold) to a salad.
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Recipe Card
Roasted Red Onions
Ingredients
- 1 large red onion
- 2 tablespoons olive oil
- ½ teaspoon Diamond Crystal kosher salt or ¼ teaspoon of fine salt
Instructions
- Preheat your oven to 400 degrees F.
- Peel the onion, slice it into ¼-inch thick slices, and separate the slices into rings.
- Spread the onion rings in a glass baking dish. Add the olive oil and toss to coat. Sprinkle the onion rings with salt.
- Roast the onions, stirring once halfway through roasting, until soft and caramelized, about 20 minutes.
Video
Notes
Add Your Own Notes
Nutrition per Serving
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Vered DeLeeuw, LL.M., CNC, has been following a low-carb real-food diet and blogging about it since 2011. She's a Certified Nutrition Coach (NASM-CNC), has taken courses at the Harvard School of Public Health, and has earned a Nutrition and Healthy Living Certificate from Cornell University. Her work has appeared in several major media outlets, including Healthline, HuffPost, Today, Women's Health, Shape, and Country Living. 
Samantha
These are absolutely delicious! I used melted butter and everyone raved about them! We used them to top burgers.
Vered DeLeeuw
I'm so glad these onions were a success, Samantha!
Susan
Excellent way to produce beautifully caramelized red onions with very little hands-on work!
Vered DeLeeuw
I'm so glad you enjoyed this recipe, Susan! I agree; Roasting is so much easier than pan-frying.