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.
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.
Video
Notes
Make Ahead Instructions: The taco meat filling can be made 2-3 days in advance (depending on the freshness of your ingredients), stored in the fridge. When ready to use, fill tacos and bake as instructed. Assembled tacos, in the shells, will keep for a few hours stored in covered in the refrigerator (the taco shells will start to soften too much if assembled for longer than a few hours before baking).Freezing Instructions: You can freeze taco meat filling in a freezer safe container forup to 3 months. Thaw overnight in the refrigerator, fill tacos and bake as directed.