Preheat your oven to 375°F (190°C).

In a large skillet over medium heat, add the ground beef and cook for 5-7 minutes until browned.

Stir in the chopped onion and minced garlic, sautéing for about 3-4 minutes.

Add taco seasoning, mixing well for 1 minute before adding black beans, corn, and diced tomatoes. Heat through for 2-3 minutes.

Fill each taco shell generously with the beef mixture, then top with shredded cheese.

Bake in the preheated oven for 10-12 minutes until cheese is bubbly and slightly browned.

Prepare fresh toppings while tacos are baking: chop lettuce, dice tomatoes, and slice jalapeños.

Serve your tacos hot, topped with lettuce, tomatoes, jalapeños, and sour cream.