If you are wondering about the best way to grill onions, then read on! I have all the tricks and tips to get perfectly caramelized grilled onions cooked on the barbecue grill. They’re drizzled with balsamic vinegar and seasoned with thyme which makes them a versatile and savory vegetable side dish.

grilled onions with balsamic and thyme

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Why We Love This Recipe For Grilled Onions

Whether they’re pickled onions, sauteed, or anything in between, onions are the backbone ingredient that adds flavor and depth to your savory dish, but these grilled onions are the star of this delicious side dish! Think of this recipe as the summer sister recipe for how to make caramelized onions! They are sweet and savory and add so much delicious flavor to a wide variety of meals!

You’re going to love the sweetness of the balsamic in contrast to the savory onion and how the process of grilling brings out the natural sugars in the onions for a caramelized effect. Use them to top off grilled steaks, burgers or add to Mexican fajitas. We also serve them as a side with Barbecue Chicken!

Key Ingredients

ingredients to make easy grilled onions with balsamic vinegar and thyme

Vidalia Onions

Vidalia onions are a type of sweet onion and have mild and less sharp flavor than yellow onions or red onions. An alternative for Vidalia is Walla Walla or Oso Sweet. 

Avocado or Olive Oil

Both oils are perfectly fine for this recipe as they both have a high smoke point. It’s really a matter of preference: avocado oil has a bit of a mild avocado flavor, while olive oil is smooth and nutty.

Balsamic Vinegar

If you don’t have balsamic, you can also use sherry vinegar or malt vinegar. 

Seasonings

The simple seasonings you’ll need for your grilled onions are coarse kosher salt, ground pepper, and dry thyme.

Step By Step Instructions For Grilling Onions

preheating the grill and slicing onions

Step 1: Preheat Grill

Preheat your grill to high heat. If you have one, I recommend using a vegetable grilling basket on top of the grill grates. Make sure to add it to the grill now so that it will be preheated too.

Step 2: Prepare Onions

Trim the root end of each onion to remove the dry and dirty roots, and rinse the onion to make sure there are no traces of soil on it. Cut the onion into ¾-inch thick slabs while leaving the root intact. This helps more of the onion rings to hold together while on the grill. 

drizzle onions in oil and grill them

Step 3: Oil and Season

Brush oil over the onion slices and sprinkle them with salt, pepper, and thyme.

Step 4: Grill

Grill the onions, turning occasionally until they’re soft and charred in some spots. It should take about 12 minutes. 

grilled onions with balsamic vinegar and thyme

Step 5: Drizzle Balsamic Vinegar and Thyme

Transfer the onions to a plate and drizzle with the vinegar of your choice. Serve and enjoy!

grilled onions sprinkled with thyme and drizzled with balsamic vinegar on a serving dish

FAQ For This Recipe

What’s the difference between grilled onions and caramelized onions?

The key difference is that to caramelize onions you need a moist cooking environment to really soften them completely, and then you can allow the natural sugars of the onion to brown as the liquid evaporates. By contrast, grilling is a dry heat cooking method, so the onions will cook more quickly and not soften as much as true caramelized onions.

Why are grilled onions sweet?

Onions are naturally sweet vegetables and when they’re exposed to high heat their natural sugars break down and begin to caramelize.

Can I make grilled onions ahead of time?

They can be grilled 3 days ahead and then served cold or rewarmed in the microwave.

How do I prevent my onions from falling apart while grilling?

To reduce the risk of the onions falling apart we leave the root intact and use a grill basket to make it easier. That way, if the onion starts to fall apart it won’t fall between the grill grates. As an alternative method, you can skewer the onions slabs with kebab or wooden skewers. Lay your onion rings flat and carefully skewer through the sides of the onion rings.

Variations to Try:

  • You can add different flavor profiles by brushing your onions with barbecue sauce or our Peach BBQ Sauce in the last minute or so it’s on the grill instead of using the balsamic vinegar. 
  • Add chopped fresh herbs such as basil, fresh thyme or dill once they come off the grill.
  • Here we focused on Vidalia onions, but you can try other varieties of onions for a stronger onion flavor such as white onions, yellow, Spanish or Bermuda.

Serving Suggestions For Grilled Onions

  • Pile these grilled onions on top of burgers.
  • Add these to whole-wheat crepes with scrambled eggs and shredded cheese for a savory breakfast.
  • Grill baguette or a hearty slice of bread (like this Whole-wheat bread) and make these into grilled onion crostini with goat cheese and olive oil.
  • Pair these with your favorite cheese in a gourmet grilled cheese sandwich.
  • Add them to a meatless or chicken quesadilla.
  • These grilled onions are the perfect addition to grilled sausage sandwiches or hot dogs.

Additional Healthy Grilled Vegetable Recipes To Try

At Healthy Seasonal Recipes, we specialize in cooking with fresh veggies and creating weeknight meals. Sign up HERE to get more produce-forward dinner ideas for FREE! If you make this recipe, please come back and leave a star rating and review. I would love to hear what you thought! Happy Cooking! ~Katie

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Grilled onions with balsamic and thyme

Easy Grilled Onions

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5 from 6 reviews

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Description

If you are wondering about the best way to grill onions, then read on! I have all the tricks and tips to get perfectly caramelized grilled onions cooked on the barbecue grill. They’re drizzled with balsamic vinegar and seasoned with thyme which makes them a versatile and savory vegetable side dish. Use them to top off steaks, burgers or add to Mexican fajitas.

Ingredients

Scale

3 large sweet onions, such as Vidalia, peeled

1 tablespoon plus 1 teaspoon avocado oil or olive oil

1 teaspoon coarse kosher salt

Freshly ground pepper, to taste

3/4 teaspoon dry thyme

1 tablespoon plus 2 teaspoons balsamic vinegar, sherry vinegar or malt vinegar

Instructions

  1. Preheat grill to high heat.
  2. Trim root end of each onion to remove dry and dirty roots. If necessary, rinse the onion to make sure there are no traces of soil on it. Cut onion into ¾-inch thick slabs leaving root intact.{This helps the onion hold together when it is on the grill.}
  3. Brush oil over the onion slices. Sprinkle with salt, pepper and thyme.
  4. Grill, turning occasionally until the onions are soft and charred in spots, about 12 minutes.  
  5. Transfer to a plate and drizzle with vinegar.

Notes

Make Ahead:

They can be made 3 days ahead and served cold or rewarmed in the microwave.

  • Prep Time: 10 mins
  • Active Time: 15 mins
  • Cook Time: 20 mins
  • Category: Side Dishes
  • Method: Grilling
  • Cuisine: Mixed

Nutrition

  • Serving Size: 3 cups, 6 servings
  • Calories: 61
  • Sugar: 1 g
  • Fat: 3 g
  • Carbohydrates: 9 g
  • Fiber: 2 g
  • Protein: 1 g

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