Roasted Onions are a surprisingly delicious roasted vegetable that makes any dinner extra delicious! Tender and caramelized but just a little bit crispy on the edges, these onions will add loads of sweet-and-savory flavor to meats, salads, meal bowls, and more.
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Why You’ll Love This Oven-Roasted Onions Recipe
- Quick Alternative to Caramelized Onions. This roasted onions recipe delivers lots of flavor and it cooks in half the time. (Everyone loves caramelized onions, but hello, who has 45+ minutes on a weeknight to caramelize them properly?)
- Sweet-Savory Balance. While caramelized onions go all in on sweet, roasted onions have a more balanced flavor; the roasting intensifies the sweetness of the onions, but they still pack in lots of savory goodness.
- Crispy and Tender. Baked onions get tender and caramelized, but the edges also get some crispy char on them, which makes them an absolute delight. It’s similar to how Roasted Brussels Sprouts have those contrasting tender centers and crispy outer leaves.
- Add Them to EVERYthing. From Crustless Quiche to Grilled Pork Tenderloin and even No Knead Focaccia, everything tastes better with thyme-infused oven-roasted onions.
- The Best Way to Use Spare Onions. You know how some stores only sell onions in bags? And then you have a WHOLE BAG of onions when you really just needed one for your Homemade Chicken Noodle Soup? Roasted onions (and Roasted Radishes) are an excellent way to use up an extras.
How to Make Roasted Onions
The Ingredients
- Onions. You can use red or yellow onions. Sweet onions like Vidalia, while delicious sliced on Air Fryer Hamburgers, are not ideal here because their higher water content will make them bake up mushy.
- Dijon Mustard. For some pep and zip. Mustard has a sharpness that works well as a complement to the sweetness of the roasted onions.
- Dried Thyme. Thyme is a classic pairing with onions (and also other roasted vegetables like Roasted Mushrooms and Roasted Butternut Squash).
The Directions
- Get Started. Peel and halve the onions.
- Cut into Wedges. Slice each onion into four wedges.
- Season. Toss the onion wedges with the remaining ingredients.
- Roast. Bake onions at 425 degrees F for 25 to 35 minutes, flipping halfway through. Season with salt and ENJOY!
Recipe Variations
- Balsamic Roasted Onions. Instead of Dijon mustard, whisk balsamic vinegar with the oil.
- Roasted Onion Slices. While I love onion wedges as a side dish, onion slices work better for piling onto a burger or sandwich. Cut 1/2-inch slices of onion and roast for 20 to 25 minutes.
Leftover Ideas
Leftover roasted onions are excellent added to an Egg White Frittata or Sweet Potato Hash for breakfast. You can make them into another dinner by serving leftovers atop a bowl of Farro Risotto or Creamy Polenta.
What to Serve with Roasted Onions
- Chicken. The flavors in these onions would pair beautifully with this Stuffed Chicken Breast recipe or these Rosemary Chicken Thighs.
- Pork. Pork and onions are a classic combination! Try this Instant Pot Pork Tenderloin or Smothered Pork Chops.
- Beef. Serve roasted onions as an accompaniment to Air Fryer Steak.
- Pasta. Brussels Sprouts Pasta with Brown Butter or any pasta with fall vibes will go well with roasted onions.
- Salads and Meal Bowls. These onions would go well with Balsamic Chicken Salad or added to a Buddha Bowl with Veggies and Tahini Dressing.
Recipe Tips and Tricks
- Use Onions That Are Similar in Size. It’s okay if you don’t have medium onions! You can use all small onions or all large onions and adjust the time accordingly. But don’t use a small onion and a large onion—the large onion wedges will still have the bite of raw onion while the small wedges are burning.
- Leave Room for Air Circulation. AKA: Don’t crowd the pan! When you pack your vegetables together, whether you’re making Roasted Cauliflower or Roasted Asparagus, they’ll end up steaming instead of roasting. This means the texture and flavor will be womp womp. Spread the onions on the pan and give them some space.
- It’s Okay if the Wedges Fall Apart. Roasted onions are all about contrasting flavors and textures; the wedges that fall apart will be crispier, which is a nice contrast to the softer, less-charred onions that stay intact.
- Season Evenly. Make sure the onions are well-coated with the oil and mustard. It’s not just for flavor, but the oil is what helps the onions achieve those perfect crispy edges in the oven.
Roasted Onions
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Ingredients
- 2 medium onions red or yellow
- 2 tablespoons extra-virgin olive oil
- 1 teaspoon Dijon mustard
- ½ teaspoon kosher salt plus an extra pinch
- ½ teaspoon dried thyme
- ¼ teaspoon ground black pepper
Instructions
- Place a rack in the center of your oven and preheat to 425°F. Line a large rimmed baking sheet with parchment paper.
- Halve each onion through its stem ends. Trim off the tip of each stem and remove the peel. Cut each half lengthwise into 3/4- to 1-inch wedges (you will have about four wedges per half). Place in the center of the baking sheet.
- Whisk together the remaining ingredients in a small bowl. Pour the oil mixture over the top and gently to coat the onions evenly. Some of the wedges will fall apart, which is fine. Spread into a single layer so that the cut sides of the wedges are touching the sheet pan.
- Roast onions for 25 to 35 minutes, until the onions are tender and lightly charred at the edges, using a spatula to flip them once halfway through. Season with a pinch of additional salt. Enjoy warm or at room temperature.
Notes
- TO STORE: Refrigerate leftovers in an airtight container in the refrigerator for up to 4 days.
- TO REHEAT: Reheat roasted onions in a 350 degree F oven until warmed through, in a nonstick skillet set over medium-low heat, or in the microwave.
- TO FREEZE: Freeze leftovers in an airtight container or zip-top freezer bag for up to 2 months. Thaw overnight in the refrigerator, then reheat as directed above.
Nutrition
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This recipe is a lifesaver! I’m always looking for easy and healthy side dishes, and this hits the spot perfectly. I love that it’s so versatile too. Made these with a sprinkle of smoked paprika and they were divine! It added extra flavor that we like. Thank you so much!
Yay! Thank you Kaila!
Perfect timing! I just picked up a giant bag of onions at the farmer’s market and was looking for ways to use them up. I made some changes, I used balsamic vinegar instead of olive oil and they were amazing! The tangy sweetness was perfect.
Just made this to go with our dinner and I’m OBSESSED! My teenagers don’t usually like onions, but they actually ate these. Thanks for sharing!
SO excited to hear that, thanks Anette!