Dice 1 onion. Heat 1 tablespoon oil in a large pan over medium-low heat. Add onion and cook for 3 to 5 minutes, until softened but not brown. Add 2 minced cloves garlic and cook for 1 minute. Stir in 2 tablespoons tomato paste, 0.5 teaspoon chili powder, 1 teaspoon paprika powder, 1 teaspoon cumin powder, 1 teaspoon coriander powder, 0.5 teaspoon oregano, 1 teaspoon sugar, and 1 teaspoon salt. Simmer over medium heat for 3 to 4 minutes.
Increase heat to high. Add 500 g lean ground beef and cook for 3 to 5 minutes, breaking up the meat with a spoon as it browns. Add roughly 3 tablespoons water and stir continuously for 5 to 10 minutes, allowing most of the liquid to evaporate. If the meat begins to stick, add a splash more water.
Preheat oven to 180°C (356°F). Heat the 12 taco shells in the oven for 5 minutes.
Arrange the cooked beef on the table with the taco shells, shredded iceberg lettuce, grated cheddar cheese, and salsa so everyone can assemble their own tacos.