If you haven't had a basic taco in a while, it's time to revisit the original. Remember the spicy beef mixture in a crisp taco shell topped with lettuce, cheese, and tomato? It's still as tasty as ever.
Heat oven to 375°F.
Heat oil in large nonstick skillet, over medium-high heat. Add onion; cook until onion is softened, about 3 minutes. Add beef; cook, stirring with wooden spoon to break up, until beef is no longer pink, 5 to 7 minutes.
Add chili powder, salt, cumin and red pepper; cook, stirring, 1 minute. Stir in tomato sauce. Bring to boiling. Lower heat to medium. Cook for about 5 minutes, stirring occasionally.
Heat taco shells in 375°F oven for about 5 minutes. Spoon about 1/4 cup meat mixture into each shell. Serve with lettuce, tomato, cheese, diced onion and taco sauce.