Remove the skin and seeds from the avocados and place the flesh in a large bowl. Add in the lime juice, garlic and salt and pepper and stir/mash to combine. Cover with plastic wrap so the wrap is touching the top of the guac. Set aside in the fridge until ready to use.
Dust the burger patties with some salt and pepper and then the spice mixture so they are coated evenly.
Toast the burger buns first in a toaster or on the grill. Cook the burgers about 5 minutes on the first side, until you start to see the juices collecting on the top of the burger. Flip and add the cheese. Cook another 5 minutes until it is cooked through.
Spread the sour cream on the bottom bun, then add the burger on top. Next spread on the guac, then add some pico, then lettuce and more sour cream. Top with the top bun and serve.