Oven Roasted Onions

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This Roasted Red Onions recipe turns the humble onion into a crave-worthy side dish. Caramelized on the edges but tender in the center!

Over my 10+ years as a personal chef, I’ve spent many many hours roasting vegetables. It’s my favorite way to serve them. So I’ve developed a technique around oven temperature, timing, slicing, and seasoning that will give you perfect results every time.

Once you taste the way roasting turns the sharp onion flavor sweet and savory, you’ll want to make these all the time for a side dish or for layering into sandwiches.

Then, try some other roasted vegetable recipes like these Roasted Mini Peppers, Roasted Broccoli, and Roasted Celery Root.

Jump to:

• Why You'll Love Roasting Onions
• 🥗 Ingredients
• How to Make Oven Roasted Onions
• Tips For Roasting Onions
• Serving Oven Roasted Onions
• Storing Roasted Red Onion
• 🧐 Recipe FAQs for Roasted Red Onions
• Other Roasted Vegetable Recipes
• 📖 Recipe
• More About Molly

Why You'll Love Roasting Onions

• With minimal prep time, these onions are an easy side dish.
• Only 4 ingredients
• Vegan, dairy-free, and gluten-free, so perfect for almost any eater
• Delicious with grilled meats, but go well with so many other dishes

🥗 Ingredients

• Red Onions: We love the sweet flavor of roasted red onions, but you can replace with yellow or white onions as well. If you want something that has the sweetness of a red onion, try a Vidalia onion instead. 
• Olive Oil: We are roasting at a high temperature, so olive oil is a good choice because of its high smoke point. You could replace this with a different oil, such as avocado oil or sunflower oil, but be sure to look for something with a similarly high smoke point. 

How to Make Oven Roasted Onions

1. Let’s talk about how to roast red onions. First, preheat oven to 450 degrees Fahrenheit. Cut 1 ½ pounds of red onions in half, then place onions cut side down and slice off each end. Peel off papery skin, then cut onions in ¾-inch-thick wedges.

2. Put onion wedges in a large bowl, and add 2 tablespoons olive oil, ½ teaspoon kosher salt, and ½ teaspoon freshly ground black pepper. Toss until onion slices separate a bit and are evenly coated in oil.

3. Line a sheet pan with parchment paper or nonstick foil. Distribute onions on the sheet pan in a single layer.

4. Roast for 15 minutes, then stir. Roast for an additional 10-15 minutes, depending on how caramelized you want the edges of your onions to be. 

5. Garnish with parsley if desired.

Tips For Roasting Onions

This red onions recipe is super versatile when it comes to other flavors. You can add herbs like rosemary or thyme to the onions, or season them with spices like chili powder, garlic salt, curry powder, or smoked paprika. You can also add a splash or two of balsamic vinegar to your sliced red onions to make balsamic roasted onions. 

Don’t crowd the onions onto a small baking sheet—they need to be distributed in a single layer so that they caramelize rather than steam. 

Make sure to look for onions that are firm with dry skin, and avoid onions that have soft spots. (That said, if you get a onion with a brown spot, you can cut that out when you are slicing the onion into wedges.)

Using nonstick foil or parchment paper on your baking sheet makes cleanup easy. Plus, the onions won’t stick to your pan. 

You could try this recipe with shallots instead of red onions. Just peel, cut in half, and roast as directed above. You may find the shallots need less time to roast. 

Roasted bell peppers and onions are a delicious combination. Just combine this recipe with my Roasted Mini Peppers recipe for an easy, but flavorful side dish. Roasted red onions and potatoes is another classic pairing.

Serving Oven Roasted Onions

Now that you have your oven roasted red onions, what to serve them with? They are delicious for a summer BBQ, as they go really well with grilled meats. But you can also stir them into a pasta dish, like this Creamy Mascarpone Pasta, or use them as a topping for sandwiches. They are also perfect in grain bowls, like in this Crispy Tofu Buddha Bowl recipe. And try serving on a charcuterie board with cheeses and cured meats. 

Storing Roasted Red Onion

Store your roasted onions in an airtight container in the refrigerator for up to 5 days. Reheating in a hot oven or air fryer will bring back the crispy edges. You can also freeze your roasted onions for up to 3 months, but note that the onions will likely get a little mushy after you defrost them. Frozen onions are best used if you’re going to put them into a cooked dish, soup, or stew rather than eating them on their own.

🧐 Recipe FAQs for Roasted Red Onions

Other Roasted Vegetable Recipes

As we said, we LOVE roasting vegetables as it’s the best way to bring out their flavor. Try these Honey-Roasted Turnips or this Roasted Broccoli. Or try one of our other favorite recipes:

If you try this recipe, we would love to hear from you! Please rate this Roasted Red Onion recipe and leave a comment below—your feedback is invaluable to us.

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📖 Recipe

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