Thaw salmon, if frozen. Rinse fish; pat dry with paper towels. Cut into two (6-ounce) pieces. Set aside.
In the bowl of a food processor or a mini-chopper combine oregano, cilantro, green onion, garlic, lemon juice, oil, salt, and pepper. Cover and process until chopped. (Or, use a knife to finely chop oregano, cilantro, green onion, and garlic. Transfer to a shallow bowl. Stir in lemon juice, oil, salt, and pepper.) Generously coat both sides of salmon with the herb mixture.
Cook the salmon on the rack of an uncovered grill directly over medium-hot coals for 6 to 8 minutes or until the salmon just begins to flake easily with a fork. To serve, cut each salmon piece in half. Makes 4 servings.