You would drop the "r" and add an "n" so that it is comen, so that it becomes "they eat". Hope this helped you!
Answer:
What food do you like to prepare in the kitchen? =¿Qué comida te gusta preparar en la cocina?
Why do you like to prepare this dish? =¿Por qué te gusta preparar este plato?
Explanation:
i hope i have understood what you meant and if you don't put a redo, i hope i've helped you.