Toufu appears in English dictionaries as a loanword from Chinese, meaning bean curd. It has been in English since at least the late nineteenth century. Open a British cookbook from 1890, and there it is: toufu. A foreign word, graciously admitted into the English lexicon.
There is one problem. No Chinese person has ever said toufu. The Chinese word is dòufu. The t- initial is a fossil of an older romanization system—probably Wade-Giles or a regional dialect transcription—that mangled the sound and left it that way. The result is a word that claims to be Chinese but is unrecognizable to Chinese speakers.
This is the peculiar cruelty of the broken bridge word. An English speaker orders toufu at a restaurant and believes they are using the authentic term. A Chinese speaker hears toufu and does not know what is being ordered. The word fails in both directions. It is not a loanword. It is a mistranslation that survived.
The same dish, in the same language, should have one name. The Chinese name is dòufu. The pinyin system, standardized in 1958 and adopted internationally, renders it as doufu. No English speaker has any phonetic difficulty with doufu. The d- is soft. The -ou- is familiar from words like soul and shoulder.
What kept toufu alive for over a century when it was clearly wrong? Inertia. Cookbooks copied older cookbooks. Dictionaries cited older dictionaries. No one stopped to ask a Chinese speaker. The word drifted through English cuisine like a typo that was never corrected.
Zhonglish recommends that all references to bean curd in English adopt doufu. The sound is correct. The spelling is transparent. The bridge is rebuilt.
Our Recommendation: Doufu. The Chinese word, pronounced correctly, for everyone.