Rinse fish; pat dry. Sprinkle with salt and pepper. Combine oil, lemon juice, and garlic; brush fillets with some of the mixture. Let stand at room temperature for 15 minutes.
Meanwhile, for salsa, in bowl, combine remaining ingredients. Set aside.
Grill the fish on an uncovered grill directly over medium-hot coals* for 4 to 6 minutes per 1/2-inch thickness of fish or until fish flakes easily with a fork, carefully turning and brushing once with the remaining lemon mixture halfway through cooking.
Remove the fish to a serving platter. Top the fish with the fresh salsa. Makes 6 to 8 servings.
To test for medium-hot heat, you should be able to hold your hand over the heat at food height for 3 seconds before having to pull away.