Recipe: A lake fish sauce requires fish, obviously. Some maintain that variety is a good thing; others suggest avoiding very oily fish, such as eel, or very strongly flavoured fish, such as sardines. For this sauce, I suggest a small chub, a whitefish, a perch, a tench or even a burbot. Remove the innards from the fish, wash them and remove fillets, taking off their skin and ensuring that no unwanted bones are left in the flesh. Pour a little extra virgin olive oil in a sauce pan and gently fry together an onion, a carrot, a clove of garlic and some chopped celery. After a few minutes add, in this order: the fish fillets, a little salt and pepper, a glass of white wine (allow to evaporate) and some tomato sauce and leave the sauce to cook and reduce. Check that the sauce is cooked and add salt if necessary.