Whisk together the olive oil, lemon zest, lemon juice, salt, and pepper.

Add the fish and gently toss to coat. Let sit for at least 15 minutes.

To grill: Preheat the grill and lightly oil the grates. Grill the fillets until the bottom turns opaque and you can see darker grill marks, 3 to 4 minutes. Flip and cook another 3 to 4 minutes, until the fish flakes easily with a fork.

To broil: Preheat the broiler. Place the fillets on a lightly greased broiler pan about 6 inches under the broiler. Broil 5 to 6 minutes, or until the fish flakes easily with a fork.

Serve with fresh lemon.