Crossword Genius

Mexican food and soda that sadly lacked hydrogen (7)

Ross

I believe the answer is:

tostada

I'm a little stuck... Click here to teach me more about this clue!

'mexican food' is the definition.
(I've seen this before)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for tostada that I've seen before include "Mexican topped pancake" , "Mexican food" , "Crisp 15 down" , "spicy food" .)

I've seen this clue in the Sydney Morning Herald.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.