Cook the jumbo pasta shells according to package instructions until al dente. Drain and set aside.

In a skillet over medium heat, cook the ground beef and onion until the meat is browned. Drain excess fat.

Stir in the taco seasoning, black beans, corn, and salsa. Cook for an additional 5 minutes until heated through.

Preheat the oven to 350°F (175°C).

Fill each cooked pasta shell with the taco filling mixture and place them in a baking dish.

Sprinkle the top with shredded cheddar cheese.

Cover the baking dish with foil and bake for 20 minutes. Remove the foil and bake for an additional 10 minutes until the cheese is bubbly and golden.

Serve hot, topped with sour cream and garnished with sliced green onions.