Easy roasted red onions are the perfect way to meal prep. Bake in the oven for use in your favorite lunch bowl, as a taco topping, or as a standalone side dish. This roasted red onion recipe is easy to reheat and can be served warmed, chilled, or at room temperature.
This post may include affiliate links. Please read my disclosure policy.
We have been on a roasting streak in the Peel house lately. Maybe it is colder than normal weather. You can check out our most recent slow-roasted tomatoes and our roasted garlic to see what I am talking about. Serious goodness!
If you find raw red onions too harsh then these oven-roasted red onions are for you. Roasting the red onions removes the spiciness allowing the sweetness to shine.
This is a very simple and straightforward recipe. and salt and black pepper. But you can add additional seasonings like lemon zest, hearty fresh herbs (we like thyme), or even spicy dried chilis.
Red Onions- This recipe works with any type of onion not just red onions.
Oil-Roasted onions are easy to make in the oven using a neutral oil like olive oil, filtered coconut, or avocado oil. And yes even melted butter.
⏲️How to Make Roasted Red Onions
Start by preheating the oven to 400 F degrees.
Step 1- Prep the Baking Sheet
Line a rimmed baking sheet with parchment paper to prevent sticking, you can also use foil. Alternately you can oil the baking sheet but if your onions are high in sugar they may still stick even with the oil making clean up a pain.
Step 2- Prep the Onions
Peel the papery layers off your onions. Your red onions should be sliced into ½ thick slices.
Thinner sliced onions may cook faster, but they also get gummy so stick with the thicker slice.
Place your red onions on the baking sheet in a single layer and lightly brush with oil and season with salt and pepper.
Add any additional seasonings at this time.
Step 3- Oven Bake
Roast the red onions until caramelized, about 15 to 20 minutes. Flip halfway through for even caramelization.
How to Make Balsamic Roasted Onions
This is a special variation of this recipe that we love to make but I didn't think it was different enough to warrant its own recipe and post.
To make balsamic and thyme roasted onions mix in the leaves of 4 fresh thyme sprigs (or ½ teaspoon of dried thyme) and 2 tablespoons of balsamic vinegar with the 2 tablespoons of oil.
Brush (or drizzle) the onions before baking. Flip halfway through the baking (still 15 to 20 minutes total) and brush (or drizzle) on an additional 2 tablespoons of balsamic vinegar.
How to Use Roasted Onions
We use this roasted red onion recipe as a standalone side dish and in some of our favorite dishes.
As a side dish, the balsamic style is recommended. Chopped up with fresh herbs and mixed into cream cheese for a roasted red onion bagel spread
Chopped and mixed with refried beans and cheese for vegetarian bean tacos.
On a vegan antipasto platter like the photo below.
More Roasted Vegetable Recipes
👩🏻🍳 Expert Tip
Did You Enjoy Making This Recipe? Please rate this recipe with ⭐⭐⭐⭐⭐ or leave a comment. It helps other wonderful people connect with my food.
Leftover roasted red onions are perfect for meal prep. Store in an airtight container for 3 to 5 days.
Roasted red onions can be eaten cold or warmed up in the microwave or in a nonstick skillet.
📖 Printable Recipe Card
Roasted Red Onions
- Preheat oven to 400 F degrees. Line rimmed baking sheet with parchment paper or lightly brush with oil.
- Cut onions into ½ inch slices. Arrange onions on a baking sheet. Brush lightly with oil and season with salt and pepper.2 red onions, 2 tablespoons olive oil or coconut oil, kosher salt and pepper
- Roast until caramelized and tender, 15 to 20 minutes. Flipping once halfway through.
- Store roasted onions in an airtight container in the refrigerator for 3 to 5 days.
- Balsamic- Add one tablespoon of age balsamic vinegar to the olive oil for extra caramelization.
- Garlic- Add 4 peeled whole cloves of garlic when roasting. Smash and mix with the onions after roasting.
- Fresh Herb- Add 6 sprigs of fresh thyme when roasting. Remove woody stems before serving.