A word that can be used to reference both a meat and a non meat food item

Solution 1:

I disagree respectfully with the first answer for several reasons.

First, "protein" is a technical word, and not everyone is sure of what it means exactly. For example, beans contain "proteins," but not the full complement found in meat.

Second, I do not think it clarifies what is confusing to me in the original. If someone does not want meat or seafood, do they get the stir fried vegetables without anything additional, or can they get something additional such as tofu?

I'd try something very simple:

"Stir fried vegetables in garlic and pepper sauce with your choice of an extra ingredient."

Then you can have your box listing the options for extra ingredients. This is basically the "X" option using English instead of algebra.