There is a lot of confusion about the term Matignon in culinary world. Every chef describe it differently. As a culinary student, just remember the following basics and you will never have to look down. Use as and when required depending upon the dish.
Matignon can be finely chopped, thinly sliced or uniformly cut like brunoise
It’s a cooked mixture of Onions, Carrots and Celery to enhance the flavor of variety of dishes in which large cuts of meats are used. This mixture is sautéed slowly in clarified butter on a low flame with ham and fresh herbs like thyme and bay leaf, finished with deglazing the pan with splash of Madeira.
Ratio of vegetables – 50% onions, 25% celery and 25% carrots
Thin slices of vegetables is also used as a base to place the meat while roasting meats to avoid drying the meat because of direct contact with the pan.
If it sounds similar to mirepoix then remember that matignon becomes part of the meal and it usually contains raw ham, while mirepoix is discarded after preparation. Mirepoix is used only to fortify the soups and sauces and variety of meats, fish and shellfishes.
When you prepare matignon without the ham or bacon the preparation is called as maitgnon au maigre.
The bed of vegetables placed on a roasting pan is called as bed of matignon.
Matignon can be served as garnish or can be served separately as a side dish to introduce with main dish to balance the additional flavor on the table, or bake it along with dish to add flavor and serve along with dish.