Teriyaki Sauce

Combine soy sauce, mirin, sake, and sugar in a small, heavy-bottomed saucepan. Stir briefly to dissolve the sugar. At this stage the mixture is thin, dark, and smells strongly of alcohol — the sake and mirin are raw. Set over medium heat and bring to a gentle simmer, stirring once or twice. Allow the alcohol to cook off before reducing: you will notice the sharp alcohol smell soften and sweeten as the sake and mirin cook out, replaced by a rounder, more caramelized fragrance.

Maintain a steady, gentle simmer — not a hard boil — and reduce the sauce for 5–8 minutes, swirling the pan occasionally rather than stirring. The sauce is ready when it coats the back of a spoon thickly and a line drawn through the coating holds for 2–3 seconds. If using cornstarch: mix it with a tablespoon of cold water to form a slurry, then whisk it into the simmering sauce and stir for 30 seconds until thickened and glossy. Remove from heat — the sauce thickens further as it cools.