01 - Heat vegetable oil in a large skillet over medium heat. Add chopped onion and cook for 2–3 minutes until softened.
02 - Stir in minced garlic and cook for 30 seconds until fragrant, being careful not to burn.
03 - Add ground beef to the skillet. Cook, breaking up meat with a wooden spoon, until browned and cooked through, approximately 5–7 minutes. Drain excess fat if necessary.
04 - Stir in tomato paste, chili powder, cumin, smoked paprika, oregano, cayenne (if using), salt, and pepper. Mix thoroughly to coat the meat evenly.
05 - Pour in beef broth or water. Simmer uncovered for 4–5 minutes until the mixture thickens, stirring occasionally. Taste and adjust seasoning as needed.
06 - Warm hard taco shells according to package directions while the beef simmers.
07 - Fill each shell with a generous portion of beef mixture. Layer with lettuce, tomatoes, cheese, sour cream, green onions, cilantro, and jalapeño if desired.
08 - Arrange tacos on a serving platter and accompany with lime wedges for squeezing over the top.