If you overcook food, you leave it on the heat for too long. The food is still food — it is not always burnt black — but it has gone past the point where it tastes or feels right. Vegetables can turn soft and dull. Meat can go dry and tough. Eggs can turn rubbery. Pasta can swell and stick. This is everyday kitchen English, not a fancy word. You overcook something (a verb): the rice, the steak, the broccoli. Cooks say it as a warning, and people at home say it when dinner has sat on the stove too long. Though actually, some foods forgive you more than others: a stew can sit a long time and still be fine, but a steak or a green vegetable cannot.

煮過頭、煮太久