Preheat an oven to 375 degrees F.
Over medium heat, cook the ground beef in a large skillet until no longer pink. Drain off any excess fat.
In a small bowl, combine the chili powder, masa corn flour, Accent seasoning, all-purpose flour, cold water and cayenne pepper until smooth and pour it into the skillet with ground beef mixture. Stir everything together and simmer for 5 minutes or until thickened.
Divide the beef mixture equally among 6 taco shells and place on a greased baking sheet lined with foil paper or parchment paper. Top each taco shell with one slice of American cheese and sprinkle some ground black pepper over them; bake in preheated oven for 8 minutes until cheese is melted and taco shells are lightly browned.
In a small bowl, mix together the tomato paste, mild taco sauce, salt, garlic powder, cumin, sugar and 1/4 cup of water. Simmer for about 3 minutes or until sauce thickens slightly.
Remove tacos from oven and top with lettuce, tomatoes and prepared sauce; serve immediately.