They eat the same foods you and I eat but it has to be dehydrated in order to save weight and room.
And it can't have crumbs, because crumbs could contaminate the instruments.
İ don't realy know, but Ive heard that there are these drinks made especialy for astronaut's. My friend told me this and he said that those drinks are like hamburgers or salad just blended strongly...
To eat in space you have to eat certain foods, for example if they want to eat ice cream they have to take the water out of it so it doesn't get messy.