Roasted onions are wonderfully flavorful and caramelized. They make a wonderful side dish or topping to meats and poultry.
Baking onions in the oven makes them tender, browned, and very flavorful. It’s a recipe that I like to make because it’s truly easy to make, yet it produces delicious results.
With the exception of the youngest – the Picky Eater – we all like it very much. It’s also a very versatile recipe – you can use the roasted onions as a topping or even as a side dish all on its own.
Cooked onions are creamy and mild
I don’t know about you, but I don’t really like raw onions. I find their pungent, sharp flavor to be quite offensive.
But something magical happens when you cook them. They become creamy and mild, almost sweet.
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 do make a wonderful, very flavorful side dish.
The ingredients you’ll need
You’ll only need three simple ingredients to make this recipe. 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), although I usually tend to use yellow onions.
Butter: I use plenty of butter – 2 tablespoons per one medium onion plus more for the pan. The butter adds wonderful flavor to the onions. Another tasty option would be to use olive oil. But personally, I prefer butter.
Kosher salt: I use kosher salt in most of my recipes, this one included. If using fine salt, you might want to use less of it, or the dish could end up too salty.
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. You can also sprinkle them with grated parmesan cheese after the first 20 minutes of cooking.
How to make roasted onions
Scroll down to the recipe card for the full details. Here are the basic steps:
1. Your first step is to peel the onions, slice off their edges, then cut them into four or five thick slices, as shown in the video below.
2. Now place the onion slices in a well-buttered rimmed baking dish. Coat them with melted butter and sprinkle them with Kosher salt.
3. The last step is to bake the onions until golden-brown. This should take about 40 minutes in a 400°F oven, and you should flip the onion slices midway through baking. Keep a close eye on them the last 10 minutes of baking to ensure they don’t burn. Your oven might run hotter than mine.
What main dishes go with roasted onions?
This lovely side dish goes really well with meat and poultry dishes. Since I bake it in a 400°F oven, I like to serve it with a main dish that I can cook in the same oven. It’s just so convenient!
So, among other choices, I often serve these onions with baked pork chops, with baked meatballs, or with beef tenderloin roast. They also make a wonderful topping for hamburgers, such as these broiled hamburgers.
What about leftovers?
Leftovers keep quite well in the fridge, in a sealed container, for 3-4 days. Reheat them, covered, in the microwave on 50% power. Leftovers are also very good when chopped and mixed into an omelet or a scramble such as this spinach and eggs scramble.
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- 2 tablespoons butter plus more for the pan
- 1 medium onion
- ½ teaspoon Diamond Crystal kosher salt
- Preheat your oven to 400 degrees F.
- Grease a square 8-inch Pyrex baking dish with butter.
- Peel the onion and slice it into 1/4-inch-thick slices, as shown in the video below. You will probably end up with five slices.
- Arrange the slices in a single layer in the prepared baking dish. Melt the butter and pour it all over the onions. Sprinkle 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 golden-brown, about 20 more minutes.