To make sauce, melt shortening in skillet.
Stir in chili powder and water.
Bring to boil, cooking and stirring until thickened.
(Should be thick enough for dipping corn tortillas.)
Cook ground beef until brown.
Add diced onion, avocado and salt; mix thoroughly.
Dip corn tortillas in sauce.
Fill with meat mixture and lots of cheese.
Roll and serve piping hot.