godan verb (-su), transitive verb
cook through; cook the inside
Rare or limited literal use for cooking something so that the inside is done. In ordinary modern cooking instructions, 煮る or 中まで火を通す is usually clearer.
「豆を芯まで煮やす」とあれば、豆の内部まで煮て火を通すという意味になる。
If it says “cook the beans through to the core,” it means to boil them until the inside is cooked.
Attested kanji spelling with high priority. As a literal culinary verb, it is much less ordinary than 煮る or 中まで火を通す.
The spelling uses 煮, associated with boiling or simmering. The exact historical formation of 煮やす is uncertain, so it is safest to treat it as a rare verb related in meaning to cooking by simmering.