Roasted Onions Side Dishes

If you’ve never had Roasted Onions, they’re a delicious side dish and have so much flavor!

In this recipe, the onions become sweet and mellow with caramelized bits as each piece softens. and softens each piece, making these onions both sweet and savory. These are perfect to Like on their own or to add to so many other recipes!

serving plate with Roasted Onions and thyme

Sweet, Savory, & So Easy!

  • Simple and inexpensive, this side goes with almost any meat.
  • Prep is about 5 minutes. Simply slice, season and bake.
  • Part of the allium family, and just Like roasted garlic, when onions are oven roasted they become mellow and sweet.
  • Add leftovers to soup, stew or my favorite, add it to gravy!

ingredients for Roasted Onions with labels


ONIONS All onions are readily available and affordable. Yellow onions are most popular in many recipes and are perfect for roasting. But we really love sweet white onions or Walla Wallas. Of course, any onion will work.

As a garnish with holiday lamb, ham, or turkey, try using pearl onions and cippolini onions. These can be baked whole.

SEASONINGS Rosemary and thyme are excellent sprigs of herbs to add to the dish as the onions roast. Add them whole across the tops of the onions for a delicate flavor or chop them finely and sprinkle over top for more herb flavor.

onions slices on a wooden board and in a dish for Roasted Onions

How to Roast Onions

Roast these in the oven until they are crisp, golden, and irresistible.

  1. Prepare the butter mixture. Slice the onions & place them in a casserole dish.
  2. Brush the onions with the butter mixture. Add water, salt, & pepper.
  3. Roast (as per the recipe below).

Depending on the preference, the material of the baking dish, and the type of onion, cooking can vary. I prefer a ceramic or glass dish and love the little crispy edges. Check the onions early and roast to your preference.

Roasted Onions in a baking dish with thyme

Best Way to Use Roasted Onions

I love to eat them warm out of the pan just as is.

There are so many ways other ways to use these roasted onions!

  • Topper: They are a delicious condiment topper for juicy turkey burgers, street tacos, or add them to an easy turkey wrap.
  • Side Dish:  Up-level a juicy oven-grilled steak by layering the top with roasted onions, or stir them into an oven veggie medley with mushrooms, carrots, and peppers.
  • Addition to: And don’t forget about adding flavor to mashed potatoes, mushroom sauce, or soup, beef stew or gravy.


Keep leftover roasted onions in a covered container in the refrigerator for up to 5 days. Reheat in the microwave or enjoy them cold in a burger or wrap. Leftovers can be added to different soups Like Cream of Onion Soup, Slow Cooker French Onion Soup, and Homemade French Onion Soup. These would go great with a thick piece of homemade bread.

Our Fave Roasted Veggies

  • Roasted Sweet Potatoes – sweet & savory
  • Roasted Balsamic Brussels Sprouts – only 5 ingredients
  • Maple Roasted Parsnips – freezer friendly
  • Roasted Delicata Squash – so easy to make
  • Garlic Roasted Broccolini – simple yet elegant!

Roasted Onions on a serving plate with thyme as garnish

5 from 1 vote

Review Recipe

Roasted Onions

Prep Time 10 minutes
Cook Time 50 minutes
Total Time 1 hour
Servings 4
Author Holly Nilsson
Roasted onions are so versatile and add flavor to so many dishes. Balsamic vinegar, butter, and some heat from the oven will make these onions crispy and caramelized. 
Print Recipe


  • 2 large sweet onions 1 ½ -2 pounds
  • 2 tablespoons melted butter
  • 1 teaspoon balsamic vinegar
  • 3 tablespoons water or broth
  • teaspoon kosher salt or to taste
  • teaspoon freshly ground black pepper


  • Preheat the oven to 400°F.
  • Whisk melted butter and balsamic vinegar.
  • Peel the onions and Cut into ½” slices, do not separate the rings.
  • Place the onions in a greased 9×13 baking dish and brush with the butter mixture. It’s ok if they overlap a little bit.
  • Pour the water into the casserole dish.
  • Season with salt and pepper and roast 40-50 minutes or until golden and tender.

Recipe Notes

Depending on the preference, the material of the baking dish, and the type of onion, cooking can vary. I prefer a ceramic or glass dish and love the little crispy edges.

Check the onions early and roast to your preference.

Leftover roasted onions can be kept in the fridge in a covered container for up to 5 days. They make a great addition to gravy, soup or stew.

Nutrition Information

Calories: 104, Carbohydrates: 13g, Protein: 1g, Fat: 6g, Saturated Fat: 4g, Polyunsaturated Fat: 1g, Monounsaturated Fat: 1g, Trans Fat: 1g, Cholesterol: 15mg, Sodium: 132mg, Potassium: 201mg, Fiber: 2g, Sugar: 9g, Vitamin A: 177IU, Vitamin C: 8mg, Calcium: 36mg, Iron: 1mg

(Nutrition information provided is an estimate and will vary based on cooking methods and brands of ingredients used.)

Course Side Dish
Cuisine American
Roasted Onions in a dish with text
Roasted Onions in a serving dish with a title
Roasted Onions in a dish with writing
Roasted Onions in a baking dish and on a plate with writing

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In this space, I am always sharing flavorful, fresh, (mostly) healthy recipes that I love to make and eat in my real, actual, every day life. If I wouldn’t eat it in real life, I won’t put in on the blog. You’re cooking for yourself, your family, your roommates, or your friends. I want you to be so excited about these recipes that you eagerly await 5pm when you can go home from work and start cooking.

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Roasted Onions Side Dishes

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