01 - Preheat oven to 350°F to prepare for warming taco shells.
02 - Heat a large skillet over medium heat. Add ground beef and cook, breaking apart with a wooden spoon, until browned throughout, approximately 5 minutes. Drain excess fat if necessary.
03 - Add chopped onion and minced garlic to the skillet. Sauté for 2 to 3 minutes until onion is softened and fragrant.
04 - Stir in tomato paste, chili powder, cumin, smoked paprika, dried oregano, salt, and black pepper. Cook for 1 minute to bloom the spices.
05 - Pour in water and reduce heat to low. Simmer for 3 to 4 minutes until the mixture has thickened slightly. Remove from heat.
06 - Arrange hard taco shells on a baking sheet. Sprinkle a small amount of shredded cheddar cheese into the bottom of each shell. Bake for 3 to 4 minutes until shells are warmed through and cheese is melted.
07 - Fill each warmed shell with the seasoned beef mixture. Top with shredded lettuce, diced tomato, remaining cheddar cheese, and optional toppings including green onions and cilantro.
08 - Serve tacos immediately alongside sour cream and salsa for individual portioning.