Fond brun, or brown stock. The brown color is achieved by roasting the bones and mirepoix. This also adds a rich, full flavour. Veal bones are the most common type used in a fond brun. Tomato paste is often added (sometimes thinned tomato paste is painted onto the roasting bones). The acid in the paste helps break down the connective tissue helping accelerating the formation of gelatin, as well as giving color to the stock.
other than water what is the most important ingredient of brown stock
bones bones bones