Clean, scale and remove fins of fish. If the fish is very large (over 1 kg) make a few shallow cuts on either side across the width of the fish. Dry fish with a towel. Brush fish all over with a little oil (preferably olive oil) mixed with lemon juice. Season with black pepper or another spice and, if you wish, fill the belly with a herb of your choice.
Place on a very clean, hot barbecue (but not too hot if the fish is very large, as it will burn on the outside before cooking inside). Refrain from moving the fish for the first 3-4 minutes. After that time, if using a barbecue grill with metal bars, give the fish a quarter turn so that it cooks more evenly (optional).
When the first side is cooked, turn the fish over using two large egg lifters (you may need the aid of a second person for this if the fish is very large), and finish the cooking. Small fish (250 g) may take only 8 mins, while a fish of more than 1 kg will take 20 mins or more.