酿 here means 'to stuff' (not 'to brew'). Hakka legend holds that migrants from northern China missed dumplings (
饺子) but lacked wheat flour, so they stuffed the pork filling into tofu instead —
酿豆腐 is the 'southern dumpling.' It's one of the three iconic
客家酿菜 alongside
酿苦瓜 and
酿茄子.