01 - Heat vegetable oil in a large skillet over medium heat. Add chopped onion and cook for 2 to 3 minutes until softened.
02 - Incorporate minced garlic and cook for 30 seconds until fragrant.
03 - Add ground beef, breaking it apart with a spatula. Cook for 5 to 6 minutes until browned and fully cooked.
04 - Drain excess fat if necessary. Stir in chili powder, cumin, smoked paprika, oregano, salt, and black pepper.
05 - Add tomato sauce and water, mix thoroughly, and simmer for 4 to 5 minutes until slightly thickened. Remove from heat.
06 - While beef simmers, heat the hard taco shells according to package directions.
07 - Fill each shell with the seasoned beef, then layer with shredded lettuce, diced tomatoes, cheddar cheese, red onion, cilantro, sour cream, salsa, jalapeño slices if using, and a squeeze of lime.
08 - Serve immediately to maintain shell crispness.