In large skillet, brown ground beef, ensuring you break up into small pieces as it browns, about 5 minutes or until no pink remains.
Over medium heat, add onion, minced garlic, chili powder, oregano, flour, cumin and cayenne pepper. Cook for about five minutes or until onions are soft.
Add beef broth and tomato sauce, stirring until slightly thickened. Cook for a further five minutes, stirring ocassionally. Allow to cool and divide into freezer containers.
On serving day
Thaw in refrigerator then heat in microwave or saucepan until thoroughly heated. Serve in pita shells. Add cheese, tomatoes, etc if desired.