Heat oven to 375°F. In 10-inch nonstick skillet, cook beef and onion over medium-high heat 5 to 7 minutes, stirring frequently, until thoroughly cooked; drain. Stir in pickles, water, ketchup, mustard and pepper.
Spoon beef mixture into 11x7-inch (2-quart) glass baking dish. Sprinkle with cheese.
Unroll dough; press into 12x8-inch rectangle. Cut into 6 squares; place on top of cheese. Brush with egg; sprinkle with sesame seed.
Bake 25 to 30 minutes or until deep golden brown.