Sauté onions in hot bacon grease till soft but not browned, add tomatoes, chiles, potatoes, water, beef base, coriander and cumin; bring to boil and reduce to simmer.
Mix ground beef with crushed chips, egg, garlic, cumin and water. Shape into marble size balls and drop in broth mixture. Simmer on medium heat for 15 to 20 minutes or until meatballs are cooked throughout.
Serve with hot flour tortillas.Makes 6