1. Scrub grill grate clean to help prevent sticking, and preheat grill to medium high. If fish still has fins, remove with a sharp knife and set aside to make fish broth, or discard.
2. Make a series of 3–4 diagonal slits across fleshy part of each side of fish between tail and head. Cuts should be deep (to the bone) to aid in more even cooking.
3. Lightly oil entire fish, including inside the cuts and in the belly cavity. Coat each fish with 1 teaspoon salt and ½ teaspoon pepper (or to taste), concentrating on cuts and cavities. Insert 2 garlic cloves or shallots deep into the belly cavities of each fish.
4. Squeeze lemon wedges into belly cavities, and line them up along the opening, skin sides out, about 3 per fish, to plug the cavity opening. Use soaked barbecue skewers or toothpicks to “pin” opening flaps together to keep pungents and lemon securely inside.
5. Reduce grill temp to medium, and oil grate. Generously recoat fish with oil and place on grill, belly side toward you, leaving enough room behind it to roll over. Cover grill, and cook, undisturbed, about 10 minutes (if fish is 2 inches thick in the middle).
6. Gently roll fish backward with spatula to flip, close grill, and cook 10 minutes more, until flesh flakes easily.
7. Use spatula to carefully work fish skin away from grill, and lift whole fish onto plate. Garnish with fresh herbs, if using, and generous lemon wedges to squeeze over all just before serving. Be mindful of small bones when enjoying.