Cut the avocado in half and remove the pit. Scoop the flesh out of the skin with a spoon and place it in a small mixing bowl. Mash the avocados with a fork until mostly smooth. Finely chop the red onion and cilantro. Stir the onion, cilantro, salt and lime juice in with the avocado. Cover with plastic wrap and store in the refrigerator for up to 12 hours.
Place the meat in a large mixing bowl. Add the cumin, chili powder, cayenne, salt, and salsa. Use your hands to thoroughly combine the ingredients. Chop the onion and chipotle pepper and add to the mixing bowl. Mix well. Add the eggs and tortilla chips and use your hands to thoroughly mix ingredients again.
Form the meat into round patties, about 1½ inches thick. Heat a nonstick frying pan over medium heat. Cook the burgers, 2-3 at a time (or however many fit in the pan). Cover the pan with a lid and allow the burgers to cook for 5 minutes, checking once or twice to avoid burning on the bottom. After 5 minutes, the bottom side should be browned and there should be little to no pink on the top side. Flip the burgers and cook uncovered for another 2-3 minutes to achieve desired browning. Also, this is a good time to add the cheese to the tops of the burgers because it will melt slightly in the hot pan.
Serve burgers on toasted buns (just 3-4 minutes under the broiler will do the trick) and top with a dollop of chilled guacamole.