How to Make It
Place pizza stone or heavy baking sheet in oven, and preheat to 450°F.
Heat a skillet over medium. Add ground beef and onion; cook, stirring occasionally, until crumbled and browned. Sprinkle with salt and 1/4 teaspoon of the pepper. Remove from heat; drain and set aside.
Stir together ketchup and 1/4 cup of the mayonnaise in a small bowl; set aside. Form dough into a 14-inch circle, and prick all over with a fork. Bake on pizza stone in preheated oven 5 minutes. Remove from oven, and spread ketchup mixture over crust, leaving a 1/2-inch border. Spread beef mixture and cheeses evenly over ketchup mixture, and top with tomato slices and pickles. Sprinkle with remaining 1/4 teaspoon pepper, and bake at 450°F until golden and bubbly, 10 to 12 minutes.
While pizza bakes, stir together mustard, pickle juice, and remaining 2 tablespoons mayonnaise in a small bowl. Top pizza with lettuce, and drizzle with mustard mixture. Cut into 8 slices, and enjoy!