Cook the ground beef in a large skillet over medium heat, breaking it into very small pieces until browned. Remove grease. Add onion and saute for a few minutes. Stir in the dry spices.

Add tomato sauce and pinto beans and stir to combine. Turn the heat to low and simmer for 5-10 minutes, stirring occasionally.

Preheat oven to 375 degrees F. Line two 9x13'' pans with the taco shells (or us a larger baking sheet to fit more).

Spoon taco mixture into tacos. Top with cheese. Bake for 10-15 minutes.

Top with a little bit of lettuce, tomatoes, and sour cream and salsa, if desired.