Your sense of taste is your best tool for establishing when a sauce is ready, says Molly Stevens, author of All About Braising (W.W. Norton, $35, www.amazon.com), so sample your sauce as it cooks. Red sauces (like tomato sauce) are relatively stress-free. They should simply taste the way you want them to taste — and if you leave one on the stove for a while, the worst that can happen is that the flavor will get richer (up to a point, of course). But if “reduce the sauce by half” is an instruction that has stumped you, use a chopstick or a wooden skewer as a gauge, suggests Stevens. Dip one end in to measure the depth of the sauce at the beginning, then dip it in again a minute or so later to compare. The bubbles will also look syrupy and pop more slowly when the sauce is sufficiently reduced. Cream sauces, on the other hand, are done when they coat the back of a metal spoon. Maroukian suggests testing the coating properties and taste by dipping a bit of the food — a piece of lamb, for example — that you want to serve with the sauce. “For the most part, the sauce should have the consistency of melted ice cream,” she says.