Space food has come a long way from the days of paste in a tube, as Canadian astronaut Chris Hadfield demonstrates in the video below.
From the Canadian Space Agency's YouTube info:
Canadian astronaut Chris Hadfield shows us his "kitchen" in space and prepares a 0-g treat. Free-floating food-eating ensues, complete with a tumbling tortilla.
Hadfield isn't the only astronaut to make news by eating a sandwich in space. In 1965 Gemini astronaut John Young snuck a corned beef sandwich into space— an action that resulted in a congressional hearing.
Here's some more images of space food. These are served on the ISS (picture from 2003):
These are from the space shuttle missions, taken at the Astronaut Hall of Fame in Florida:
They've even made burgers in space, though these don't look all that appetizing: