Roasted Balsamic Onions

Realistically, most weekday dinner “sides” in our household consist of 10-minute brown rice or some sauteed broccoli. But sometimes, the steam-in-bag side standard is Not Good Enough. Sigh.

Fortunately, roasted balsamic onions (with balsamic glaze!) look wayyyyy fancier than they are. Basically, all you have to do is 1) slice, 2) brush, 3) bake, and 4) glaze. Fair warning: do not use a not-rimmed baking sheet. I made this mistake for the photos and all kinds of onion juice dripped and burned on the bottom of my oven and the apartment filled with smoke and it was a whole thing. Live and learn.

ANYWAY, I hope you have fun with this slightly “elevated” side dish; pair it with a simple chicken or fish. It’s as tasty as it is easy. Fun tip: these are extremely versatile as leftovers, so I always make an extra sheet. Throw a slice on a sandwich, burger, omelet, or grilled cheese for a burst of texture and flavor, or cover the onions in hot broth with extra pepper and a handful or Parmesan for a quick onion soup. Bon appetit!

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Roasted Balsamic Onions Recipe

These sweet and sticky roasted onions are packed with flavor, and they look pretty too.

Makes: 2-3 servings

Roasted Balsamic Onions Recipe

Prep time:

Cook time:

  • 2 large yellow onions, peeled and sliced horizontally into 1/3-inch slices
  • 2 tablespoons olive oil, plus more for greasing the baking sheet
  • 1 tablespoon plus 2/3 cup balsamic vinegar, divided
  • 1 teaspoon Italian seasoning
  • 2 teaspoons maple syrup
  • Salt to taste
  • Pepper to taste

  1. Preheat your oven to 375 degrees Fahrenheit and lightly grease a large rimmed baking sheet.
  2. In a small bowl, whisk two tablespoons olive oil with one tablespoon balsamic vinegar, Italian seasoning, salt, and pepper to make a marinade. Be somewhat generous with the salt and pepper; add a pinch of each.
  3. Place the onions on the baking sheet and gently brush them with the oil and vinegar mixture, reserving about a tablespoon of marinade for brushing the onions halfway through baking.
  4. Bake the onions for 35-40 minutes, or until golden brown and translucent. Brush the onions with the remaining marinade after about 20 minutes of baking.
  5. While the onions bake, add the 2/3 cup of balsamic vinegar and maple syrup to a small saucepan and bring it to a boil over high heat. Once boiling, stir the vinegar and reduce the heat to medium so that the vinegar simmers to reduce for ten-fifteen minutes. The finished reduction will be somewhat viscous and sticky, but should still pour easily. A note: the hot reduction will appear more liquid-y than the cooled reduction, so be careful not to wait until the vinegar is very sticky to remove the heat.
  6. Remove the onions from the oven and drizzle them with balsamic reduction. Enjoy.

Notes and Nutrition Information

  • These onions will keep in the refrigerator for about three days.

  • You can likely fit about three onions worth of slices on a large baking sheet if you’d like to scale up the recipe—three large onions will serve about 4-5 people.

  • The onions are safe to freeze for up to six months, but I recommend making soup or an omelet with them once defrosted as the texture will be less hearty than desired for a stand-alone side dish.

  • One third of the recipe as written contains approximately 149 calories, 10 grams of fat, 13 grams of carbohydrates, 1 gram of protein, 2 grams of fiber, 7 grams of sugar, and 58 milligrams of sodium.