1. Preheat the oven to 450 degrees F. and place an empty baking sheet on the middle rack.
2. In a medium bowl, combine the black beans, corn, tomatoes, scallions, cumin, chili powder, avocado, salt and black pepper; set aside.
3. Working on a lightly floured surface, roll the pizza dough into a 13-inch circle. Transfer to warmed baking sheet and crimp the edges slightly to form a lip at the edge of the crust. Top with black bean mixture, sprinkle with the cheese and bake 20 minutes or until crust is golden brown. Cut into 8 slices and serve.