Making the best grilled onions has never been easier! Wrap sliced Vidalia onions in a foil packet and grill until tender. Enjoy caramelized onions on top of burgers, cauliflower steaks, grilled vegetables, and so much more!
When it’s too hot outside (ok, or basically all summer long), if I’m making dinner, I’m grilling. It’s easy, doesn’t make a huge mess in my kitchen, and honestly requires just about zero dishes which I’m always down for. Especially because that means I can enjoy a cocktail on the patio just a little bit longer that way…
So it’s no surprise that I’ve basically found a way to make whatever we’re craving on the grill, including caramelized onions. Give me a piece of foil and I’ll turn just about anything into a foil packet ready to grill!
While grilling a foil packet of sliced onions doesn’t quite get the same golden brown color that caramelizing them on the stove does – unless you cook them over the flame (more on that later), the result is tender, melt-in-your-mouth, deeply flavored onions that are perfect on just about anything.
Ingredients You’ll Need for Grilled Onions
Are you ready for this super simple ingredient list?! Here’s what you’ll need:
- Vidalia Onions: these sweet onions are perfect for caramelizing on the grill. Feel free to swap for another type of yellow or sweet onion if needed.
- Butter: just a little bit to add a silky finish. If you want to make these vegan, feel free to substitute olive oil.
- Garlic and Onion Powder: to boost the onion flavor. I’ve also made it without, and while still delicious, we love the extra flavor.
- Salt and Pepper: add to your preferred taste. Don’t skip the salt as it is going to bring out the flavor of the onions!
How to Make a Foil Packet
As mentioned, foil packets are my go-to for anything that needs to be grilled but can’t just nicely fit on top of those grill grates. And it’s so easy to do.
I highly recommend using heavy-duty aluminum foil. Regular foil is prone to tearing; if it’s all you have, be sure to use two layers of it to prevent any holes.
Start by tearing a piece of foil that is large enough to wrap up over the produce. I like to have a piece that’s about 22 inches long.
Then, to prepare the onions, thinly slice them by cutting the onion in half and removing the outer layer. Place the onion half cut side down, then thinly slice across the onion. Be sure your knife is sharp, and that you are using the “claw” method, placing your fingertips up and down on the onion.
Slice the onions as evenly as possible to ensure even cooking. The thinner they are, the faster they will cook and the more caramelized they will get.
Place the sliced onions on top of the foil, then toss with garlic and onion powder, and salt and pepper. Dot with the butter.
Fold up the long edges of the foil. I pull the sides up, aligning them together, and then fold them over each other to create a seal. Once the top is folded over itself, then fold in the sides to create the full foil packet. We are sealing all edges to keep the steam inside.
Try to leave space in the foil packet around the onions. In other words, don’t press down on the foil itself. Leaving room inside will help us later on when we’re ready to shake it up.
How to Grill Onions
Now for the easy part, because it’s pretty much hands-off from this point on!
Heat the grill to medium-high heat, around 450°F. If the grill is hotter, that’s ok too, as it will fluctuate somewhat depending on what else you’re grilling. Place the foil packet on the grill over direct heat for a more caramelized result, and indirect to prevent any deep caramelization and to reduce any burning risk.
Let the onions cook away for about 25-30 minutes, shaking the packet about halfway through the cooking time. If you’d rather, you can also carefully open the packet and stir the onions halfway through the cooking time as well.
Once the onions are ready, again, very carefully open the foil packet and allow the steam to escape.
Stir the onions to make sure all the flavors are combined, then serve as desired! That’s it, really such an easy side dish or condiment to your favorite grilled meals!
Ways to Use Grilled Onion Slices
The beauty of grilling onions in a foil packet is the endless ways to use them (in addition to their deliciousness, of course!). Here are a few of our favorite ways to enjoy them:
- On top of burgers (meat or veggie!)
- Alongside roasted vegetables
- Paired with grilled steak or cauliflower steak
- On top of a flatbread pizza (like on this breakfast pizza!)
And if you’re looking for more foil packet recipes, why not give this Rosemary Salmon in a foil packet a try, or these Potato and Corn Hobo Packets. Throw it all together and you’ve got yourself one easy dinner, dishes free!
Easy Grilled Onions in Foil
- 1 large Vidalia onion or yellow onion thinly sliced
- 1/4 tsp onion powder
- 1/4 tsp garlic powder
- Salt to taste
- Freshly ground black pepper to taste
- 1 Tablespoon unsalted butter diced
- Heat grill to 450°F.
- Cut a piece of heavy duty foil (or two pieces if using regular foil) approximately 22 inches long.
- Place thinly sliced onion in the center of the foil and toss with onion and garlic powder, and salt and pepper. Dot the top with butter.
- Pull the long edges of the foil up, folding them onto each other to create a seal. Then fold in the short edges of the foil to create the packet, making sure all edges are sealed, and leaving enough space in the foil packet for the onions to move when you shake it.
- Place the foil packet on the grill over direct heat (but not a direct flame). You can also place it over indirect heat to reduce any risk of burning the onions. Cook for 25-30 minutes, shaking the foil packet halfway through. You can also gently open and stir the onions around halfway through.
- Gently open the foil packet, allowing the steam to escape. Stir the onions before serving and allow to cool slightly.