Answer:
What has ears but can't hear?
This is a Japanese food consisting of cooked vinegared rice sushi-meshi combined with other ingredients, usually raw fish or other seafood.
A time when they're green. A time when they're brown. But both of these times, cause me to frown. But just in between, for a very short while. They're perfect and yellow. And cause me to smile.
I'm a food made of flour, water, and yeast or another leavening agent, mixed together and baked. You need me to make a sandwich.
The sun bakes them, The hand breaks them, The foot treads on them, And the mouth tastes them. What are they?
By Moon or by Sun, I shall be found. Yet I am undone, if there's no light around