"which food" is a grammatically correct and usable phrase in written English.
It is used to ask for specific information about food. For example: "Which food do you want for dinner tonight?".
Which food stall would you take him to?
Which food stall would you take her to?
His father practiced traditional Chinese medicine, in which food plays a major role.
Then paint or draw a composition in which food is the primary subject.
No, remember when we asked you which food you can't live without, and you said sushi?
Walking, they found, sped the rate at which food moved through the stomach.
David Cameron is in denial about the scale of the hardship which food banks represent.
This is just one of the many ways in which food can make us happy.
The body covering is a tough cuticle, through which food is absorbed.
It is also a space that the museum rents out for social events, at which food and drinks are served.
Watch here Even before I get to the stages, I'll have checked out which food stalls are set up.
