Tofu was invented in China over 2,000 years ago, traditionally attributed to 刘安 of the Han Dynasty. There are countless varieties: 嫩豆腐 (soft tofu), 老豆腐 (firm tofu), 豆腐干 (dried tofu), 臭豆腐 (stinky tofu).
usage
The idiom 刀子嘴豆腐心 means 'sharp tongue but soft heart' - literally 'knife mouth, tofu heart'. It describes someone who sounds harsh but is actually kind.