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These roasted onions are wonderfully flavorful and caramelized. They're the perfect side dish or topping for meat and poultry dishes.
Even if you're not a fan of onions in their raw state (I'm not), I think you will love them oven-baked. They are mellow and sweet.
Raw onions are sharp, but something magical happens when you cook them. They become creamy and mild, almost sweet. Baking onions in the oven makes themtender, browned, and flavorful. The same is true for sauteed onions, by the way.
This roasted onions recipe is easy, yet it produces delicious results. It's also a versatile recipe - you can use the onions to top steaks and burgers or as a side dish.
Jump to:
- Ingredients
- Variations
- Roasted Onions Instructions
- Expert Tips
- Recipe FAQs
- Serving Suggestions
- Storing Leftovers
- More Onion Recipes
- Foodie Newsletter
- Recipe Card
Ingredients
You'll only need three simple ingredients to make these roasted onions. The exact measurements are included in the recipe card below. Here's an overview of what you'll need:
- Medium onions: White or yellow onions work well in this recipe (here's the difference between different onion types), although I usually tend to use yellow ones.
- Butter: I use plenty of butter - two tablespoons per medium onion plus more for the pan. The butter greatly enhances this dish.
- Kosher salt: I use Diamond Crystal kosher salt.
Variations
- You can coat the onions with extra-virgin olive oil instead of butter. It's good, but not as good as butter.
- Since the onions are so flavorful, I don't usually add any other seasonings. But if you'd like, you can season them with garlic powder and oregano, using ¼ teaspoon of each.
- After flipping, you can also sprinkle the onions with 2 tablespoons of grated parmesan cheese.
Roasted Onions Instructions
Scroll down to the recipe card for detailed instructions. Here's an overview of the steps for making this recipe:
Your first step is to peel the onions, slice off their edges, then cut them into five thick slices.
Place the onion slices in a well-buttered rimmed baking dish. Coat them with melted butter and sprinkle them with Kosher salt.
Bake the onions until golden brown. This should take about 40 minutes in a 400°F oven. Flip the slices midway through baking.
Serve the roasted onions immediately.
Expert Tips
- Keep a close eye on the onions during the last ten minutes of baking to ensure they don't burn. Your oven might run hotter than mine. Their edges should be dark brown, not black.
- You can double this recipe and use a 9 X 13-inch Pyrex pan.
Recipe FAQs
Is this a topping or a side dish?
We don't often think about onions as a separate side dish. We tend to use them as an ingredient in other recipes. But in this case, they make a delicious side dish!
Why do onions become sweet when they're cooked?
Onions contain a relatively large amount of sugar. According to the USDA, a medium onion contains nearly five grams of sugar - that's more than a teaspoon. During the cooking process, the large sugar molecules are broken down into smaller ones, and those have a sweet taste.
Are yellow and white onions interchangeable?
White onions are sweeter and milder than yellow ones. They're not as pungent when served raw.
I wouldn't use yellow onions in a recipe that calls for raw white ones. But if a recipe calls for cooking yellow onions, using white onions is fine.
Serving Suggestions
Roasted onions pair well with meat and poultry. Since I bake them in a400°F oven, I like to serve them with a maindish I can cook in the same oven.
So, among other choices, I often serve them with baked pork chops, baked meatballs, or beef tenderloin roast.
They also make an excellent topping for hamburgers and steaks, including broiled hamburgers, turkey burgers, bison burgers, tri-tip roast, New York strip steak, and ribeye steak.
Storing Leftovers
You can keep the leftovers in the fridge, in a sealed container, for 3-4 days. Reheat them, covered, in the microwave at 50% power.
Alternatively, chop the leftovers and mix them into an omelet or a scramble, such as spinach and eggs scramble, fluffy scrambled eggs, or egg white omelet.
More Onion Recipes
- Sauteed Onions
- Pickled Red Onions
- Roasted Red Onions
Recipe Card
Roasted Onions Recipe
Theseroasted onionsare wonderfully flavorful and caramelized. They're the perfect side dish or topping for meat and poultry dishes.
Prep Time15 minutes mins
Cook Time40 minutes mins
Total Time55 minutes mins
Course: Side Dish
Cuisine: American
Servings: 2 servings
Calories: 123kcal
Author: Vered DeLeeuw
Ingredients
- 2 tablespoons butter plus more for the pan
- 1 medium onion
- ½ teaspoon Diamond Crystal kosher salt or ¼ teaspoon of any other salt
Instructions
Preheat your oven to 400°F. Grease a square 8-inch Pyrex baking dish with butter.
Peel the onion and slice it into ¼-inch-thick slices. You should get five slices.
Arrange the slices in a single layer in the prepared baking dish. Melt the butter and pour it over the onions. Sprinkle them with Kosher salt.
Roast the onions until the bottoms are golden, about 20 minutes.
Turn the onion slices to the other side and bake them until golde brown, about 20 more minutes.
Serve immediately.
Video
Notes
- You can double this recipe and use a 9 X 13-inch Pyrex pan.
- Keep a close eye on the onions during the last 10 minutes of baking to ensure they don't burn. Your oven might run hotter than mine. The edges should be deep brown, not black.
- Since the onions are so flavorful, I don't add any other seasonings. But if you'd like, you can season the onions with garlic powder and oregano, using ¼ teaspoon of each. You can also sprinkle them with grated parmesan cheese after flipping them.
- You can keep the leftovers in the fridge, in a sealed container, for 3-4 days. Reheat them, covered, in the microwave at 50% power. Alternatively, chop the leftovers and mix them into an omelet or a scramble.
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Nutrition per Serving
Serving: 0.5recipe | Calories: 123kcal | Carbohydrates: 5g | Protein: 0.7g | Fat: 11g | Saturated Fat: 7g | Sodium: 363mg | Fiber: 1g | Sugar: 2g
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Cup measurements refer to the standard American cup, which is 240 milliliters. Most of my recipes are low-carb (or keto) and gluten-free, but some are not. Please verify that a recipe fits your needs before using it. Recommended and linked products are not guaranteed to be gluten-free. Nutrition info is approximate, and the carb count excludes non-nutritive sweeteners. Nutrition info may contain errors, so please verify it independently. Recipes may contain errors, so please use your common sense when following them. Please read these Terms of Use carefully before using any of my recipes.
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About the Author
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. Click to learn more about Vered.
