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. Everyone loves caramelized onions, but hello, who has 45+ minutes on a weeknight to caramelize them properly? (Psst—never believe any recipe that tells you to caramelize onions over medium-high heat for 5 minutes. It’s a lie!) This roasted onions recipe delivers lots of flavor and it cooks in half the time.
- Sweet-Savory Balance. Let’s talk more about that flavor! 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 are an excellent way to use up an extras.
How to Make Roasted Onions
- 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).
- 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!
- Roasted Onions and Peppers. Add thick slices of bell peppers with the onions.
- Roasted Onions and Potatoes. Follow my recipe for Oven Roasted Potatoes, but use 1 pound of potatoes and 2 medium onions. Roast the potatoes for 20 minutes, then add the onions.
- Roasted Carrots and Onions. Follow my recipe for Roasted Carrots, but use half the amount of carrots and add 2 onions. You can use the seasoning option listed in the roasted carrot recipe or the more savory seasoning from these roasted onions—both will work!
- 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.
- 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.
Meal Prep Tip
Cut the onions up to 1 day in advance. Refrigerate the wedges in an airtight storage container until you’re ready to cook.
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, Stuffed Pork Tenderloin, or Smothered Pork Chops.
- Beef. Serve roasted onions as an accompaniment to Air Fryer Steak or Instant Pot Beef Stroganoff.
- Pasta. Toss the onions with Sweet Potato Pasta with Brussels Sprouts or Brussels Sprouts Pasta with Brown Butter. 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.
Recommended Tools to Make this Recipe
- Sheet Pans. The edges keep the veggies from falling into your oven.
- Fish Spatula. My favorite for flipping vegetables. It’s not just for fish!
- Non-slip Cutting Board. If you cook a lot, I recommend a dedicated cutting board just for onions to keep their flavor out of Fruit Salad.
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.
- 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.
- 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.
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