Oven Roasted Onions are a healthy, no-fuss vegan side that's flavor-packed and easy to make. Caramelized sweet onions are roasted in olive oil, salt and pepper, thyme, and rosemary until tender.
Roasted Onions are an easy side for a cozy meal. They require minimal prep and cleanup, cook easily on a sheet pan, and go with just about everything. Add other hearty vegetables to the mix, like potatoes, for a roasted vegetable medley.
These roasted sweet onions taste delicious with cozy dishes, like Roasted Chicken, Bavette Steak, and other roasted vegetables like Butternut Squash or Maple Roasted Brussel Sprouts and Carrots. Add a drizzle of balsamic vinegar for a rich, tangy explosion of flavor!
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About Oven Roasted Onions
- Taste - Roasting the onions brings out their rich flavor and light sweetness.
- Texture - The onions are caramelized with a light crunch.
- Effort - All you need to do is cut the onions, season them, then roast them!
- Time - It takes about 5 minutes to prepare the onions then 40 minutes to roast them.
Ingredients
- Sweet onions - We prefer sweet onions because they have a sweet flavor but are not overpowering. Varieties include. Walla Walla, Texas Sweets, Maui, and Vidalia. We cut them in half at the root to hold the layers together. You can also cut the onion into quarters if you are using a large onion so it will be easier to cook.
- Olive oil - Baking the onions in extra virgin olive oil provides the perfect texture - firm on the outside and tender on the inside.
- Kosher or sea salt - Salt accentuates the rich flavor of the onion.
- Pepper - Freshly ground black pepper adds a little spice.
- Herbs - Add fresh or dried herbs like fresh thyme, rosemary, sage, or a blend for extra flavor.
See recipe card for quantities.
Substitutions
- Medium yellow onions - Opt for yellow onions because they have a strong flavor but are not overpowering. If you opt for a medium yellow onion, cook the onion a little longer, as yellow onions have a lower water content than sweet onions and take longer to cook.
- Oil - Instead of extra virgin olive oil, use avocado oil, grapeseed oil, or coconut oil.
Variations
- Balsamic vinegar - Add 1 tablespoon of balsamic vinegar for a rich sweetness and complexity.
- Butter - Add 1 teaspoon of butter to the center of each onion half to make it more moist.
- Brown sugar - Add a pinch of brown sugar for a sweeter caramelized final dish.
- Shallots - Use shallots for a delicate onion flavor and decrease the cook time.
Instructions
- Prepare onion - Heat the oven to 400°F. Use a sharp knife to cut the onion in half at the root. Remove the dry outer layers of onion paper and cut off the tip of the onions. (Photo 1)
- Season onion - Place the onions on a parchment paper-lined baking sheet cut-side up. Generously drizzle the onions with olive oil and season with salt, freshly ground black pepper, and dried fresh herbs, like rosemary, thyme, sage, parsley, or a blend of choice. (Photo 2)
- Roast onions - Bake the onions on the middle rack for 35-45 minutes, or until tender and golden brown, turning over halfway. To test doneness, use a paring knife to pierce into a few layers of the onion through the side. If it goes in easily, the onions are done. (Photo 4 and 5)
- Serve - Transfer the roasted onions to a serving dish and season with more salt, freshly ground black pepper, and herbs, if desired. Enjoy immediately.
Pro tip - If you are using large onions, you can cut them into quarters so they will be easier to cook.
Storage
Store leftover roasted onions in an air-tight container in the refrigerator for up to 3 days. When you are ready to enjoy these easy roasted onions again, reheat them in the oven at 300°F for 10 minutes or until warm.
Recipe FAQs
Yellow, red, or sweet onions are the best because they are sweet and mildly flavored. White onions would be too pungent.
No, there is no need to soak them. These onions are delicious just seasoned and roasted.
Yes, as the onions roast they soften and become caramelized with a light crunch.
Yes, while it takes a long time to roast onions, they can definitely overcook if you cook them too long or at too high heat.
Cooking tips
- Be sure to get the olive oil between the onion layers so the layers cook thoroughly.
- Use similar sized onions and don't overcrowd the pan so the onions cook evenly.
- Figure out what main course you want to make ahead of time and make it while the onions roast so all dishes are ready around the same time.
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Oven Roasted Onions
Equipment
- 1 knife
Ingredients
- 2 medium sweet onions cut in half at the root
- 2 tablespoon olive oil plus more if necessary
- kosher or sea salt
- freshly ground black pepper
- fresh or dried herbs rosemary, sage, thyme, a blend
Instructions
- Prepare onion - Heat the oven to 400°F. Use a sharp knife to cut the onion in half at the root. Remove the dry outer layers of onion paper and cut off the tip of the onions. Place the onions on a parchment paper-lined baking sheet cut-side up. Generously drizzle the onions with olive oil and season with salt, freshly ground black pepper, and dried fresh herbs, like rosemary, thyme, sage, parsley, or a blend of choice.2 medium sweet onions, 2 tablespoon olive oil, kosher or sea salt, freshly ground black pepper, fresh or dried herbs
- Roast onions - Bake the onions on the middle rack for 35-45 minutes, or until tender and golden brown, turning over halfway. To test doneness, use a paring knife to pierce into a few layers of the onion through the side. If it goes in easily, the onions are done.
- Serve - Transfer the roasted onions to a serving dish and season with more salt, freshly ground black pepper, and herbs, if desired. Enjoy immediately.
Notes
- Cut large onions into quarters so they are easier to cook.
- Use similar sized onions and don't overcrowd the pan so the onions cook evenly.
- Get the olive oil between the onion layers so the layers cook evenly.
- Figure out what main course you want to make ahead of time so you can make it while the onions roast.
- Use sweet onions, such as Walla Walla, Texas Sweets, Maui, and Vidalia.
- If you opt for a medium yellow onion, cook the onion a little longer, as yellow onions have a lower water content than sweet onions and take longer to cook.
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