Grilled Scallops with Honeydew-Avocado Salsa

Finely grated lime zest, plus 2 tablespoons fresh lime juice

extra-virgin olive oil, plus more for drizzling

honeydew melon, rind removed and melon cut into 1/4-inch dice (2 1/2 cups)

Hass avocado, cut into 1/4-inch dice

Salt and freshly ground black pepper

large sea scallops