01 - Heat the vegetable oil in a large skillet over medium heat. Add the chopped onion and cook for 2–3 minutes until softened.
02 - Add minced garlic and cook for 30 seconds until fragrant.
03 - Add ground beef. Cook, breaking up meat with a spoon, until browned and cooked through, about 5–7 minutes. Drain excess fat if needed.
04 - Stir in tomato paste, chili powder, cumin, smoked paprika, oregano, cayenne (if using), salt, and pepper. Mix well.
05 - Pour in beef broth or water. Simmer uncovered for 4–5 minutes until thickened, stirring occasionally. Adjust seasoning to taste.
06 - Meanwhile, warm hard taco shells according to package instructions.
07 - Fill each shell with beef mixture, then top with lettuce, tomatoes, cheese, sour cream, green onions, cilantro, and jalapeño if desired.
08 - Serve immediately with lime wedges on the side.