In a medium mixing bowl combine black beans, diced tomatoes, taco seasoning and 1/2 cup of the shredded pepper jack. Mix to combined and set aside.
In a small bowl beat together the egg and water and set aside.
Place the 4 pie dough rounds on a floured work surface. Using a 3-inch round cutter cut out 32 dough circles.
Place about a teaspoon of the black bean mixture into the center of 1/2 of the dough circles. Place 1 dough circle on top of bean mixture and gentle press down with your finger to seal it to the bottom piece of dough. Crimp the edges with a fork. Repeat with remaining dough and filling.
Place all 16 formed pinata pockets onto two baking sheets. Brush the tops with egg wash and sprinkle each with remaining cheese. Bake for 15 minutes.