8 small bone-in, skin-on chicken leg quarters, preferably organic (each about 12 ounces) 4 cups store-bought lemonade, such as Minute Maid 2 cloves garlic, finely grated 1/4 cup Dijon mustard 1 tablespoon dried oregano 1 tablespoon dried minced onion 2 teaspoons cumin seed Kosher salt and freshly ground black pepper Canola or vegetable oil, for the grill 3 large lemons