Grilled Onions Recipe

Preheat and prepare onions

Preheat your grill to medium-high, about 400–450°F (205–230°C). Peel the outer papery skin from each onion, trim the root end just enough to remove loose skin but keep most of the root intact so the layers stay together while grilling. Trim the stem end flat so onions sit evenly on the grill.

Slice onions

Cut each onion crosswise into 1/2- to 3/4-inch thick slices (or into thick wedges if preferred). Reserve any broken outer layers to grill as smaller pieces. Pat slices dry with paper towel to remove excess moisture — this helps them caramelize.

Make oil/butter mixture

In a small bowl, whisk together the olive oil and melted butter (melt the butter gently). Stir in kosher salt, black pepper, and garlic powder if using. This mixture both seasons and helps prevent sticking.

Brush and oil the grill

Brush the grill grates clean and oil them with a paper towel dipped in oil or use a high-heat nonstick spray. This prevents sticking and gives good grill marks.

Brush onions

Brush both sides of each onion slice generously with the oil/butter mixture. Reserve a tablespoon of the mixture for basting during cooking. If using thyme, sprinkle some leaves on the cut surfaces.

Grill onions

Place onion slices directly on the preheated grill in a single layer. Grill with the lid closed for 4–6 minutes per side until they develop deep grill marks and become tender. After flipping, baste with the reserved oil/butter mixture. For thicker slices or wedges, grill 6–8 minutes per side. Use a spatula to flip carefully to keep slices intact.

Cook until tender

Check doneness by piercing with a fork — onions should be soft and slightly translucent inside with a caramelized exterior. If needed, move onions to a cooler part of the grill and close the lid to finish cooking for a few more minutes without burning.

Transfer grilled onions to a platter. While still hot, drizzle with balsamic vinegar if using and sprinkle with chopped parsley. Squeeze a little lemon over them for brightness if desired. Taste and adjust seasoning with additional salt and pepper to taste.

Serve immediately as a side dish, on burgers or sandwiches, or chop and fold into salads, grain bowls, or tacos. Leftovers keep covered in the refrigerator for up to 4 days; reheat gently on the grill or in a skillet.