to become roasted or parched (e.g. beans, tea leaves); to be roasted by heat (archaic usage)
火にかけた豆がじょじょに煎れて、部屋に香ばしい匂いが広がった。
The beans put over the fire gradually roasted, and a toasty smell spread through the room.
昔の茶師は、火加減を見て茶葉が煎れるのを確認した。
Old tea masters watched the heat and checked when the tea leaves were roasted.
to be irritated or annoyed (archaic)
些細なことで彼は煎れているように見えたが、すぐに落ち着いた。
He seemed irritated by a trivial matter, but he calmed down soon.
古い日記には『煎れて候ふ』といった表現が見られる。
In old diaries you can see expressions like '煎れて候ふ' (was irritated).