Each dish has its secrets and its most appropriate spices and products. You could even say that there are products that are very typical and appropriate for certain things.
In some types of cuisine, for example, almost every traditional dish uses onions and carrot. Usually, you cut them finely and fry them before anything else, if there is no meat. If the meat is raw, it is fried before the vegetables. After a slight change color or softening (onions and carrots), add other products, then spices, etc.
Even if we can call onions (carrots not so) basic product based dishes. In different areas of the world have various combinations of products that build upon the culinary feats of chefs.
Mirepoix is the basis for French dishes. Used very often, even not only in France, these few products in combination are known worldwide. You know well that the French names are fairly common even in other countries.
Mirepoix is actually a combination of several types of vegetables. In this case we talk about onion, carrot and celery. These three vegetables should be included in equal parts. Using these three products, you can begin very French and non-French dishes. They make soups, various stews, even sauces.
These three ingredients - celery, onion and carrot are the backbone of the dish. Their combination provides unmatched flavor to all dishes. In different parts of the world, this base is different - sometimes in name only, other times it is with other products.
As Mirepoix is mainly suitable for dishes with meat, whether there is any difference if cooked fish? An unbeatable combination of French cuisine, which is used for fish, bears the same name, but contain different products.
Mirepoix for fish uses leeks, which are the replacement for the carrot and go with the onion and aromatic celery.