to evaporate / (of cooking) to steam / torch made from hemp stalks or bamboo (old) / finely chopped firewood (old)
蒸
=
艹
+
烝
:
James II of England's (zh) second attempt at feeding the masses (烝) involves a heap of artificial lawn (艹). In front of the engine ((e)ng1) he cooks it producing a lot of steam (蒸) and making it into a stew.