To prepare salsa, combine first 6 ingredients. Cover and chill 2 hours.
To prepare fish, melt butter in a large nonstick skillet over medium-high heat. Sprinkle 1 tablespoon cilantro, garlic, salt, and black pepper evenly over 1 side of fillets. Add fillets, cilantro side down, to pan; cook 3 minutes. Turn, and cook 3 minutes or until fish flakes easily when tested with a fork. Serve with salsa.