- In a large mixing bowl, combine the ground beef and taco seasoning mix. Mix until well incorporated, but do not overwork the meat. 
- Divide the mixture into four equal portions and shape them into burger patties. Season both sides with salt and pepper. 
- Preheat your grill or stovetop skillet over medium-high heat. Cook the burger patties for about 4-5 minutes on each side, or until they reach your desired doneness. 
- During the last minute of cooking, sprinkle shredded cheddar cheese on top of each patty and cover to melt. 
- Toast the hamburger buns on the grill or in a toaster until golden brown. 
- Assemble the burgers by placing a patty on each bun, then top with shredded lettuce, diced tomato, a dollop of sour cream, salsa, and avocado slices. 
- Serve immediately and enjoy your delicious Taco Burgers!