Grilled Eggplant and Peppers

Preheat a charcoal or gas grill. Rub eggplants, bell peppers, chiles, and onion with olive oil in a large bowl. Grill vegetables over medium-hot heat until eggplants are soft, about 10 minutes; the skins of the peppers and chiles are blistered and charred, 10–20 minutes; and the onion is soft, about 30 minutes. When vegetables are cool enough to handle, peel, stem, and seed peppers and chiles, trim eggplants, and peel onion, then thickly slice vegetables and transfer to a medium bowl. Add remaining olive oil, garlic cloves, and salt to taste. Set aside to let marinate for at least 1 hour or cover and refrigerate overnight.