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How to Grill Onions

Sharp and pungent raw onions are a love-it-or-hate-it accoutrement for many. But grilled onions? That’s a different story.

With a balanced, sweet and smoky flavor, grilled onions are a uniquely delicious treat. You’ll be hard-pressed to find someone who disagrees!

Looking for simple instructions for how to grill onions? You’ve found them!

Read on to learn all about how to make grilled onions like a pro!

Red onions will grill marks on a charcoal grill. How to grill onions.

How to Prep Onions for Grilling

How do you prepare onions for grilling? There are several different preparations you can try.

Keep reading to learn all about different methods for slicing and seasoning onions to prepare them for grilling.

Different Ways to Slice Onions for Grilling

You can slice onions in several different ways for grilling. Select one of the three methods below for the best results.

Skewered Onion Rounds

To slice onions into rounds that won’t fall apart, use wooden skewers to space the slices evenly and hold the layers together.

Start by placing a peeled onion on its side (stem and root ends facing out). Then, beginning about an inch from the root, spear a skewer through the entire onion.

Then, using a sharp, clean chef’s knife, slice the root off, cutting halfway between the root and skewer. Cut again half an inch from the other side of the skewer.

Repeat this process until you’ve reached the stem. You’ll have even, skewered slices about an inch thick. Anywhere between three-quarters of an inch to one and a half inches is ideal for grilling.

Wooden skewers are best, because you can use your knife to trim the ends once you’ve got each slice speared individually.

Onion Wedges

Wondering how to make grilled onion wedges that won’t fall to pieces on the grill?

The answer is simple: keep the root core intact and it will hold the layers of the onion wedges together.

Start by placing the onion on its side. Make a single cut lengthwise, slicing the entire onion in half from root to stem. It’ll be easy to peel the skin off after halving the onion like this first.

Then, you can slice off the brown and dirty end of the root, but don’t go too deep into the onion. Keeping the root core intact will prevent the layers from separating as the onions cook on the grill.

Finally, slice each of the onion halves lengthwise down the middle. You will then have four evenly sized onion wedges.

Thinly Sliced Onions

Try thinly slicing your onions for a classic, versatile grilled onion preparation.

French cut sliced onions on a cutting board.

Perfect for topping steaks and burgers, thinly sliced grilled onions are also great in soups, grilled cheese sandwiches, and countless other recipes.

To thinly slice an onion for grilling, start by placing the onion on its side. Then, use a chef’s knife to slice at about half-inch increments starting from the root end and moving in toward the stem. Cut at a slight angle away from your body.

You can also use a mandoline slicer to create thin, even onion slices for grilling. (Be careful with these kinds of kitchen tools – the blades are very sharp!)

Kitchen Safety PSA

Any time you’re cooking over heat or handling sharp objects, keep best practices for personal safety in mind.

Always keep your eyes and full attention on your task while working with open flame, knives or other sharp tools.

It’s best to wear short sleeves when grilling. Long sleeves can be rolled up, as long as they are tightly secured at least five inches above the wrist.

Person slicing onions with a chef's knife.

You should also make sure to keep food prep and cutting surfaces clean and dry. Wipe up spills and clean up messes right away to keep your work area safe.

New to using knives? Consider also wearing a cut-resistant glove on your stabilizing hand while slicing onions for grilling.

Marinating and Seasoning Grilled Onions

Learning how to grill onions is super simple! Start with some easy prep work and just a couple basic ingredients.

Onions are already full of flavor, and grilling brings out their natural sweetness while adding a smoky taste as well. So they don’t need much in terms of added seasoning.

Keep reading to learn how to marinate and season onions to prepare them for the grill.

Oils and Butters

Grilling onions on an outdoor barbeque grill? Use a marinating brush to lightly baste the onions with oil before seasoning them. This prevents them from burning on the grill in addition to adding flavor and moisture.

Many grilled onion recipes call for extra virgin olive oil, but avocado oil also works well for grilling.

Butter and ghee are great for infusing grilled onions with rich flavor. These options work best for making grilled onions in a grill pan. Coconut oil could also be used as another non-dairy alternative.

Spices and Herbs

Keep it simple and season your onions with sea salt and freshly ground black pepper after brushing them with oil.

Red onion rounds brushed with oil and seasoned with spices.

Or mix it up by dusting them lightly with a blend of your favorite herbs and spices. Try a dash of paprika for a little added kick!

How to Grill Onions on a Charcoal Grill

Grilling onions over charcoal is ideal for infusing them with a robust, smoky flavor.

Here are three easy steps to follow to learn how to grill onions to perfection on a charcoal grill.

Step 1: Prep the Onions

Following the instructions above, start by cleaning, slicing, and seasoning your onions.

For grilling over a charcoal barbeque, skewered round slices or wedges are perfect choices. Larger cut pieces are less likely to slip through the grate as the onions cook and shrink.

Step 2: Build a Two Zone Fire

Make a two-zone fire by banking coals on one side of the grill and leaving the other half empty.

This creates a hot zone over the coals and cool zone on the other side.

Step 3: Grill Onions on Cool Side

Grill your onions on the cool side of the grill. This will have them cooking on high but indirect heat.

Flip the onions after ten to fifteen minutes, then cook for another ten to fifteen minutes on the other side. Flipping the onions only once makes for the most distinct and attractive grill marks.

If the onions begin to look dry, add moisture and prevent burning by brushing them with another light layer of oil or marinade.

The onions will be ready when they’re golden brown and slightly tender. Total cook time should be about twenty to forty minutes.

How to Grill Onions on a Gas Grill

Learn how to grill onions on a gas grill by following the three steps below!

Grilled onion halves.

Step 1: Prep the Onions

Prep your onions according to the earlier instructions. Skewered round onion slices at least one inch thick or wedges with intact root cores are best for outdoor grilling.

Step 2: Preheat the Grill

Next, fire up your grill. Set the temperature to 400 degrees.

Preheat for five to ten minutes.

Step 3: Grill Onions over Low Heat

Turn the burners to low just before placing your onions on the grill.

Cook on low heat for twenty to forty minutes total, turning every ten minutes (ideally, only once).

Baste your onions with a little oil or marinade if they start to look dry.

You know your grilled onions are ready when they’re golden brown, crispy and tender.

How to Grill Onions in a Grill Pan

No outdoor barbeque? No problem. You can still enjoy smoky, savory grilled onions cooked right inside your kitchen!

Onion quarters and rounds with grill marks in a grill pan.

Keep reading to learn how to grill onions on the stove using a griddle, skillet, or other grill pan.

Step 1: Prep the Onions

One advantage of learning how to grill onions on the stove is that you can experiment with a greater variety of slicing styles. No more looming threat of losing small pieces of your grilled onions down into the grate of an outdoor grill!

Grilling onions in a pan is perfect for making thinly sliced grilled onions. But you can easily grill wedges or thicker round onion slices this way as well. Go with whichever style of slice is best for the intended use for your grilled onions.

Step 2: Warm the Skillet

Once you’ve prepared your onions, preheat your skillet or cast iron grill pan over medium heat.

Add your sliced onions, butter or oil, salt, and other seasonings of choice.

Step 3: Cook Onions over Medium Heat

Stir frequently while cooking over medium heat to prevent onions from burning.

Remove the onions from the pan once they’re golden and slightly transparent, cooking for at least five to seven minutes or until onions reach your desired texture.

When making grilled onions on the stove, don’t lower the heat.

Slowly sauteeing onions over low heat results in very soft, heavily caramelized onions. Perfectly grilled onions should reach a light level of caramelization only. Cooking them faster over higher heat allows you to leave your balanced, savory-sweet grilled onions with a little al dente crunch as well.

Onions looking dry before they’re finished cooking? Sprinkle a tablespoon of water over the grilling onions to plump them up.

Frequently Asked Questions about How to Grill Onions

Keep reading for answers to common questions about making grilled onions!

Different varieties of onions.

Which onion is best for grilling?

For grilled onions with a predominantly sweet flavor, choose a sweet onion variety like Maui, Vidalia, or Walla Walla. Grilled sweet onions are especially great when thinly sliced for use in soups and sandwiches.

Red onions with their spicier flavor are also great for grilling. Slice red onions into three-quarter inch thick rounds for burger toppings. Or cut them into wedges, grill, and drizzle lightly with balsamic glaze for a simple savory side dish.

White onions have a crunchy texture and very strong onion flavor. This makes grilled white onions perfect for use in salads and salsas that don’t need any added sweetness.

Can you freeze grilled onions?

Yes, you can freeze grilled onions! This can be helpful in cases of accidental overproduction or as a preservation strategy for a large onion harvest.

Just allow your grilled onions to cool completely before placing them in airtight freezer bags and freezing.

Use frozen grilled onions within about three months. You can thaw them overnight in the fridge, or throw them right into a cooked recipe in frozen form.

Now You Know How to Grill Onions!

Thick onion rounds grilled on a flat grill.

Now you know all about how to grill onions. All you need to do now is select one of the three methods described above, fire up the grill, and start cooking!

And to learn more about all things onions, including how to grow your own at home, visit our Onions page.