Choose an assortment of onions for the best presentation. Serve as an accompaniment to grilled steak or chicken.
Trim leek tops and bottoms and wash thoroughly in several changes of cold water. Slice through lengthwise. Peel sweet onions and cut in ½-inch crosswise slices. Trim tops and root ends of scallions and spring onions. Drizzle with olive oil and season liberally with salt and pepper.
Grill over medium heat, turning as needed. Remove onions to serving dish as they’re cooked – the scallions will cook quickly, while the leeks will take longer. Before serving, drizzle with additional olive oil.