Tex Mex Burgers with Guacamole

0 Combine beef, seasoning, salt (if using), and black pepper. 
2 Gently mix them together (using your hands works best) just until everything is blended.
4 Form into 4 even patties. 
6 Gently press the center of each patty so that there is a slight indent in the middle (this will help the burgers to stay flat as they cook).
8 Prepare an outdoor grill or, if cooking inside, heat a grill pan or skillet over medium heat. 
10 Brush grill or pan with cooking oil and add burger patties.
12 Sear on both sides until burgers are cooked to your liking. In the last minute of cooking, top each burger patty with a slice of cheese.
14  Set burger patties aside and cover to keep warm. 
16 Toast hamburger buns.
18 Assemble burgers by filling hamburger buns with guacamole, burger patties, and other toppings.