01 - Preheat oven to 350°F.
02 - In a large skillet over medium heat, cook the ground beef, breaking it apart with a spoon, until browned (about 5 minutes). Drain excess fat if needed.
03 - Add chopped onion and garlic; sauté 2–3 minutes until softened.
04 - Stir in tomato paste, chili powder, cumin, paprika, oregano, salt, and pepper. Cook 1 minute.
05 - Add water, reduce heat, and simmer for 3–4 minutes until thickened. Remove from heat.
06 - Arrange taco shells on a baking sheet. Sprinkle a little cheese in the bottom of each shell. Bake for 3–4 minutes, until shells are warmed and cheese is just melted.
07 - Fill each shell with beef mixture, then top with lettuce, tomatoes, remaining cheese, and desired toppings.
08 - Serve immediately with sour cream and salsa on the side.