Cut gutted fish lengthwise, season with olive oil and sea salt. Cook covered on herbs, garlic and olive oil steam without turning. Steam quite strongly and rapidly processes foods thermally and the food will be cooked quickly (depending on size).
Cut gutted fish lengthwise and cook in a small amount of water with root vegetables and other vegetables, sea salt and olive oil. Cook depending on the size of the fish, but keep compact and solid. When the fish is cooked, strain the root vegetables and you will have a very good broth.
Broth remaining after cooking in either method can be used for risottos, pastas and sauces.