Space Food: (Top row) Italian Vegetables, Potatoes au Gratin, and Dried Pears.

(Bottom row) Salmon, Frankfurters, and Tea with Lemon
Weight and volume have always been primary design factors for every piece of hardware launched into space. The Shuttle is no exception. Weight allowed for food is limited to 3.8 pounds per person per day, which includes the 1 pound of packaging for each person each day.
Foods are individually packaged and stowed for easy handling in the zero gravity of space. All food is precooked or processed so it requires no refrigeration and is either ready to eat or can be prepared simply by adding water or by heating. The only exceptions are the fresh fruit and vegetables stowed in the fresh food locker. Without refrigeration, the carrots and celery must be eaten within the first two days of the flight or they will spoil. The main categories of space food are: Rehydratable (R) Food, Thermostabalized Food, Intermediate Moisture (IM) Foods, Natural Form (NF) Foods, Irradiated (I) Meat, Condiments, Shelf Stable Tortillas

MEAL PREPARATION
Meal preparation and consumption will involve a series of steps. A general meal scenario is as follows:
1. Collect meal tray and utensils
2. Display preselected meal on the computer
3. Locate food using location display function
4. Prepare food items for heating
5. Place items to be heated in oven
6. Enter cook control codes and press "start"
7. Rehydrate beverages
8. Place beverages on meal tray
9. Retrieve refrigerated foods
10. Place refrigerated food in meal tray
11. Retrieve items from oven
12. Place heated foods in meal tray
13. Eat
14. Place used containers in trash compactor
15. Clean and stow meal tray and utensils
Curtesy of NASA