How to Make It
Preheat a gas grill to medium-high (400°F to 450°F). Place beef and ranch mix in a medium bowl. Using your hands, gently mix until blended. Divide mixture into 4 equal portions, and shape each into a patty about 3 1/2 inches wide. Sprinkle all over with salt and pepper.
Place burgers on oiled grates; grill, covered, until outside is slightly charred, 4 to 5 minutes per side for medium, or until desired degree of doneness. Top each burger with a cheese slice during last minute of cooking time. Remove from grill, and transfer to a work surface; let rest 5 minutes. Coarsely chop burgers.
While burgers rest, stir together sour cream and ranch dressing in a small bowl until blended. Arrange chips on a rimmed baking sheet. Spoon pico de gallo over chips, and sprinkle with Mexican cheese. Top evenly with chopped burgers. Place baking sheet on grates; grill, covered, until cheese is melted, 2 1/2 to 3 minutes.
Dollop evenly with guacamole and sour cream mixture. Sprinkle with tomatoes, fried onions, and pickles.