Stocks, Soups and Sauces
Stocks
A stock is flavoured liquid from bones, mirepoix (2:1:1 onion, carrot, celery), aromatics in a sachet or bouquet garni, and cold water. White stocks use unroasted bones and start in cold water so impurities rise and can be skimmed; brown stocks use roasted bones and go into hot water. Simmer, never boil, or fat emulsifies and the stock clouds. Beef 6–8 h, chicken 3–4 h, fish 30–45 min. Never salt a stock. Remouillage is a second extraction; glace is a heavy reduction.
Mother sauces and thickeners
Béchamel (milk + white roux), velouté (white stock + blond roux), espagnole (brown stock + brown roux + tomato), tomato, and hollandaise (emulsified butter and yolk) are the classical mothers, with derivatives such as Mornay, suprême and demi-glace. Roux is equal weights butter and flour; the longer it cooks, the darker and less thickening it becomes. Alternatives: beurre manié, cornstarch slurry, arrowroot, liaison (yolk plus cream), and reduction. Hollandaise is held at 60–70 °C; hotter and it breaks.
Soups
Clear soups (broth, consommé clarified with a raft of egg white, ground meat, mirepoix and acid), thick soups (cream, purée, bisque, chowder) and specialty soups. Consommé depends on the raft forming a mat that traps particles; it must never boil.
Rule of thumb: about 100 g of cooked roux lightly thickens roughly 1 L of liquid to a coating consistency; scale up for medium and heavy bodies.
Traps: boiling stock; salting stock; adding flour to hot fat instead of the reverse; over-reducing an emulsion sauce; calling a purée a bisque.