In professional kitchens, to pinçage in the case of a braise or stew or a brown stock means to add a tomato product, most typically tomato paste, during the browning step and let that develop into a rusty color before carrying on with deglazing. This is done for flavor nuance but primarily for the "rust" color it lends to the final product.
Most brown stocks, stews, and braises where the main food item is seared follow the same general steps:
You sear the meat
You remove the meat and add in the mirepoix and other vegetable items and sweat those out.
You add garlic and toasting spices in the final minute as to not burn them.
You pinçage with tomato paste
You deglaze with wine or another acid or simply water to pick up the fond.
You add the braising liquid, the sachet and simmer.
Pinçaging is an optional step but one you will see quite frequently as it does help to develop depth of flavor and provide for a more rustic final result.