These roasted onions are tossed in a blend of herbs and spices and baked into tender, caramelized perfection, for a sweet and delicious side everyone will love. Great with all proteins, minimal work on your end (take that caramelized onions)–introducing your new favorite roasted vegetables.
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Are Roasted Onions Healthy? Keto?
Onions are rich in both vitamins C and B, as well as sulfur compounds. They’re considered a nutrient-dense food because of their low calorie count (about 44 calories in a medium onion).
- Nutrient value when cooked: raw onions have a higher concentration of sulfur compounds, while most other nutrients will generally stay the same (more here).
- Carb count: 1 medium onion contains 11 grams of carbs and 3 grams of fiber–they’re not a particularly low carb vegetable, so feel free to eat less or skip if they don’t work with your eating plan.
How To Cut Onions For Roasting
Cutting an onion can be difficult, but this method makes it easy–plus we only need halves or quarters. Here’s how:
- Remove and discard the stem (not the root end) from the onion.
- Leaving the root intact, remove only the dark brown tip of the root end. (This makes it easier to slice the onion without all the layers separating).
- Peel the onion, I find this is easiest to do by pulling the peel as you remove the stem or root tip.
- Now slice your onion either in half or into quarters.
Ingredients For Roasted Onions
Roasted onions don’t need much to be delicious–olive oil, salt, and pepper are all that’s required, but here’s how you can make this even more special:
- Opt for fresh: olive oil quality degrades over time, and fresh garlic and thyme are significantly more flavorful than garlic powder or dried thyme (although either can be used in a pinch).
- Dijon you love: all dijon recipes are different, so make sure you like the taste of yours on its own.
What onions are best for roasting?
Yellow onions are the best for roasting, sauteeing, and caramelizing, as they hold up well in high heat. They also have more sulfur than other onions, which becomes sweet as it cooks. (Psst–sulfur is also why yellow onions make you cry when you chop them).
Here are a few other varieties and what to expect if you use them instead:
- Red onions are more mild and sweet.
- White onions are similar to yellow onions but have a slightly sweeter flavor.
- Sweet onions are larger than yellow onions, and (obviously) sweeter.
More Ways to Season Onions
Onions are naturally loaded with flavor, so you can go as simple or as wild with your seasoning as you like. Here are some ideas for you:
- Simple: salt, pepper, and olive oil.
- Sassy: add some red pepper flakes or a pinch of cayenne.
- Herbaceous: try other fresh herbs like minced rosemary or oregano.
- Sweet(er): balsamic or sherry vinegar to finish.
- Mix in other veggies: some of my favorite vegetables to roast with onions include roasted bell peppers, roasted zucchini, and roasted asparagus.
How to Make Roasted Onions
After you’ve peeled and prepped your onion, the rest is easy. Here’s how to make roasted onions with loads of flavor:
The dressing. Whisk dressing ingredients together in a bowl.
The onions. Place onions in a large bowl, and cover with dressing. Toss to coat.
Now bake. Place onions cut side down in a baking dish, and drizzle extra dressing from the bowl. Roast until tender and caramelized along the edges.
Storing and Reheating
Roasted onions can be stored in the fridge in an airtight container for 3-4 days. Simply reheat in the microwave when you’re ready to eat. I don’t recommend freezing these roasted onions, they’re best made fresh.
What To Do With Leftovers
As delicious as these roasted onions are simply reheated, there are so many more ways you can maximize your leftovers. Try slicing and…
- Adding to eggs, like scrambles, omelets, egg muffins, or a frittata.
- Sandwich upgrade, any kind of meat and dressing will benefit!
- Over grains, with other roasted veggies and crumbled cheese (I love goat cheese or feta here).
- Burger topping, with a quality aioli and a juicy burger.
More Roasted Veggies You’ll Love
- Roasted Broccolini
- Roasted Brussels Sprouts
- Parmesan Roasted Broccoli
- Roasted Cauliflower Steaks
- Roasted Eggplant
Roasted OnionsPrint Recipe Pin Recipe
- 3 yellow onions
- 1/4 cup olive oil
- 1 teaspoon Dijon mustard
- 1 teaspoon garlic minced
- 1/2 tablespoon thyme leaves minced
- 3/4 teaspoon kosher salt
- 1/4 teaspoon freshly ground black pepper
- Preheat oven to 400 F, and grab a baking dish, or oven safe pan.
- Slice the stem off of each onion. Now, leaving the root intact, slice just the very tip off that’s dark brown in color–this will help keep the onion layers together. Now slice your onion through the center, and place onion halves in a large bowl.
- In a small bowl whisk together the olive oil, dijon, garlic, thyme, salt, and pepper. Pour over the onions and toss well to coat.
- Place onions slice side down on prepared baking dish or pan. Drizzle additional dressing over the tops of your onions. Bake in the oven until your onions are tender and the bottoms are caramelized about 30-40 minutes.
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