Toss the lettuce, tomatoes, corn, 3/4 cup pico de gallo and the vinegar in a large bowl; season with salt and pepper. Divide among plates or shallow bowls.
Shape the ground beef into four 4-inch-wide patties and season both sides with the taco seasoning and a generous pinch each of salt and pepper. Heat the olive oil in a large nonstick skillet over medium-high heat. Add the patties and cook, turning once, until well browned, 4 to 6 minutes.
Top each salad with 1 beef patty. Drizzle any juices from the skillet over the patties. Top with the remaining 1/4 cup pico de gallo and dollop with the sour cream. Sprinkle with the cheese and tortilla strips.