Next, prepare the velouté or demi-glace sauce that forms the base of the chaud-froid preparation. For high-quality sauce chaud-froid, you must start with a base sauce that is full-flavored, smooth, and of the proper nappé consistency.
It is best to prepare the base sauce at least one day ahead and refrigerate it overnight before modifying it. The flavor of most sauces improves with mellowing time. The rest also allows any excess fat that might be in the sauce to rise to the surface and solidify for easy removal. The presence of fat in a base sauce for chaud-froid work may cause the finished sauce to be grainy and have a poor mouthfeel.