godan verb (-ru)
boil down sake/mirin to reduce alcohol
Cooking technique used to remove alcohol from sake, mirin, or similar liquids by boiling, while retaining flavor.
みりんを煮切ってから料理に使うと、アルコールが飛んでまろやかになる。
If you boil down the mirin before using it in cooking, the alcohol evaporates and the flavor becomes mellow.
煮詰める means to boil down a liquid to thicken or concentrate it, not specifically to remove alcohol.
Compound of 煮る (to boil, simmer) and 切る (to cut off, finish). Literally 'boil-cut', referring to boiling off the alcohol content.