Preheat your oven to 400°F (200°C).

Arrange the hard taco shells upright in a baking dish.

In a medium skillet over medium heat, brown the ground beef and diced onion for about 5–7 minutes until cooked and translucent.

Stir in minced garlic and taco seasoning; cook for an additional minute.

Pour in your tomato sauce or salsa, stirring gently. Simmer for about 5 minutes.

Spoon the meat mixture into each taco shell, filling about three-quarters full.

Sprinkle shredded cheese over the filled taco shells.

Bake for 10-15 minutes until cheese is bubbly and shells are golden brown.

Top with fresh vegetables like lettuce, tomatoes, and red onion.

Serve warm with sour cream or guacamole on the side.