"Do you eat salt?"
Translation:Ĉu vi manĝas salon?
The Esperanto present tense can be used where English would use either present simple ("I eat") or present continuous ("I am eating").
If you're going to match the Esperanto present tense to just one of those, it would be the present simple ("I eat"), since the present continuous can be said more explicitly as mi estas manĝanta. (Which is grammatically very similar to the English: mi "I", estas "am", manĝ-ant-a "eat-ing", using "to be" + a present participle.)
But the Esperanto present continuous is not required as it is in English -- often, just the simple present is used for current actions as well.
Ĉu vi manĝi salon? does not work grammatically.