These garlicky grilled potatoes came to my backyard menu during a busy summer when I needed a set-it-and-forget-it side that still brought real flavor to the table. I remember whisking guests out of the kitchen and straight to the patio, tossing a foil packet onto a hot grill, and letting the aroma of sweet onions and thyme draw everyone close. The magic is that the potatoes steam in their own juices inside the foil, then pick up just enough char to crisp the edges without any fuss. Over time, this became the side I make when I want all the comfort of roast potatoes without heating the oven. Baby Yukon Golds turn buttery and tender, while the garlic mellows and perfumes every bite. The sweet onion caramelizes just enough to taste jammy, and the thyme infuses its woodsy fragrance into the olive oil. It is the kind of side that makes grilled chicken sing, steak feel special, and grilled tofu or fish feel complete. Even better, it is a no-mess solution for cookouts, weeknights, and the first warm evening when the grill finally returns to action.

Ingredients

• Baby Yukon Gold potatoes: Choose firm, smooth potatoes about 1 to 2 inches wide. Their thin skins and creamy texture turn buttery on the grill. Small, uniform sizes ensure even cooking.
• Garlic: Whole peeled cloves mellow and sweeten inside the foil. Look for firm, heavy heads with tight skins. Avoid pre-minced jars for the freshest, cleanest flavor.
• Sweet onion: A large sweet onion, like Vidalia or Walla Walla, adds caramelized sweetness. Cut into chunky pieces so they withstand the heat without burning.
• Olive oil: Use a good everyday extra-virgin olive oil for richness and to help crisp the edges. About 1/4 cup evenly coats 3 pounds of potatoes.
• Fresh thyme: Woodsy sprigs perfume the packet as it steams. Four fresh sprigs are perfect; if using dried, use 1 teaspoon and sprinkle evenly.
• Kosher salt and black pepper: Coarse kosher salt distributes evenly on the cut surfaces, and freshly ground pepper gives the potatoes a gentle bite.

Instructions

Preheat the grill: Heat your grill to medium-high (about 425 to 450 degrees Fahrenheit). Clean and oil the grates so the foil packet does not pick up any lingering flavors. Steady, even heat ensures fully tender centers and lightly crisped edges. Build the foil packet: Lay two sheets of heavy-duty aluminum foil, each about 24 inches long, crosswise so they overlap. Press into a shallow bowl shape with raised sides. Double layering prevents punctures so steam stays sealed inside. Layer the vegetables: Add the potatoes to the center. If any are larger than 2 inches, halve them so everything cooks evenly. Scatter the garlic cloves and onion chunks over the top to distribute the flavor throughout the packet. Season and toss: Drizzle with 1/4 cup olive oil, then add the thyme sprigs. Season generously with kosher salt and freshly ground pepper. Using clean hands or tongs, toss everything right on the foil until each piece is lightly coated. Seal tightly: Fold the long sides of the foil up and over to meet, then crimp to seal. Roll and crimp the short ends to form a tight pouch with a bit of headspace. A good seal traps steam for tender potatoes while preventing leaks. Grill to tender: Place the packet on the grill over direct heat, seam side up. Cook for 25 to 30 minutes, turning once halfway. Potatoes are done when a fork slides in easily and edges are just beginning to crisp. Serve hot: Open the packet carefully, directing steam away from your face. Discard thyme sprigs, taste, and adjust seasoning. Serve immediately while the potatoes are steamy and the edges are still crisp.

Storage Tips

Cool leftovers to room temperature within 1 hour, then transfer to an airtight container. Refrigerate for up to 4 days. Reheat on a sheet pan at 400 degrees Fahrenheit for 8 to 10 minutes to re-crisp, or warm gently in a covered skillet with a teaspoon of oil. For freezing, spread cooled potatoes on a sheet pan to freeze individually, then move to freezer-safe bags for up to 2 months. Reheat from frozen in a hot oven at 425 degrees Fahrenheit for 12 to 15 minutes. Avoid storing a raw foil packet at room temperature due to garlic-in-oil safety concerns; keep it refrigerated until grilling.

Ingredient Substitutions

No Yukon Golds? Use baby red potatoes in the same amount. They stay firm and pleasantly creamy. If you only have larger potatoes, cut into 3-centimeter chunks so they cook evenly. Swap sweet onion with yellow onion or 2 large shallots for a more delicate taste. Replace fresh thyme with 1 teaspoon dried thyme or 1/2 teaspoon dried rosemary. If you prefer butter richness, add 2 tablespoons of plant butter or regular butter after grilling, tossing while hot. For a touch of heat, add 1/2 teaspoon crushed red pepper flakes before sealing the packet. Lemon zest sprinkled at the end brightens everything without changing the cook time.

Serving Suggestions

These potatoes are a natural partner for grilled steak, chicken thighs, burgers, and salmon. For a vegetarian spread, pair with grilled portobellos and a big tomato-cucumber salad. I like to finish the potatoes with a squeeze of lemon, a shower of chopped parsley, or grated Parmesan for those who eat dairy. Serve directly from the opened foil packet on a wooden board for a casual, rustic look, or transfer to a warm platter. A side of garlicky aioli or herby chimichurri turns them into a standout with minimal effort.

Cultural Background

Foil packet cooking became popular in mid-20th-century American grilling culture, prized for convenience and minimal cleanup. The method is essentially a modern riff on en papillote, where food steams in its own juices in a sealed wrapper. Potatoes and onions have long been campfire staples, and this version carries that tradition to the backyard grill with olive oil and fresh herbs. Yukon Golds, developed in the 1960s, brought a naturally buttery flavor and thin skin that made them a favorite for roasting and grilling alike. This dish honors that lineage while fitting right into contemporary outdoor cooking.

Seasonal Adaptations

In spring, fold in sliced scallions and finish with lemon zest. Summer loves additions like halved cherry tomatoes or corn cut from the cob, added during the last 10 minutes. For fall grilling, toss in smoked paprika and a handful of sliced bell peppers. Winter oven method is easy: bake the sealed packet on a sheet pan at 425 degrees Fahrenheit for 30 to 35 minutes, opening for the last 5 minutes to brown. Around the holidays, tiny rosemary sprigs add a festive aroma, and a sprinkle of pomegranate arils before serving brings a bright pop of color.

Meal Prep Tips

Wash and dry the potatoes a day ahead, peel the garlic, and cut the onion so assembly is just a quick toss with oil and seasoning. Build the packet in the morning, refrigerate, and grill by evening. To feed a crowd, split into two packets for faster, more even cooking and to keep portions hot at the table. Leftovers become incredible breakfast potatoes: re-crisp in a skillet and serve with eggs or fold into a veggie frittata. If you are packing for camping, wrap each packet again in a third sheet of foil for durability, label with a marker, and stack flat in a cooler.

There is a special kind of joy in opening a foil packet to perfectly tender, fragrant potatoes that practically serve themselves. Make this once, and it will slip into your rotation, ready to tag along with whatever you are grilling next.