Preheat the grill to medium. Oil the grill pan. Rinse the fish inside and out under cold running water and pat dry with kitchen paper.
Put the lemon juice, oil, and salt and pepper to taste in a bowl and whisk together. Brush the mixture inside and outside the fish and sprinkle over the herbs. Place on the prepared grill pan.
Cook the fish under the preheated grill, basting frequently, for 5 minutes on each side, until golden brown.
Meanwhile, mix together the garlic and parsley. Sprinkle the garlic mixture over the cooked fish and serve hot or cold, accompanied by lemon wedges and salad leaves.