In a large bowl, mix together the ground beef, taco seasoning mix, bell pepper and onion using your hands. Form into 6 patties.
Lightly oil the grill grate. Cook burger patties for 5 minutes per side, or until well done. Place buns cut side down onto the grill to toast during the last minute or so. Top each burger with a slice of cheese before removing from the grill. Serve burgers on toasted buns topped with salsa and sour cream.