Heat oven to 400°F. Brown ground beef with bell pepper in large nonstick skillet over medium heat 8 to 10 minutes, breaking beef up into 3/4-inch crumbles. Pour off drippings. Stir in tomatoes and oregano; continue cooking 5 to 7 minutes or until liquid has evaporated. Remove from heat; stir in cheese. Set aside.
Sprinkle cornmeal evenly over rimmed baking sheet. Unroll pizza dough lengthwise on baking sheet, straightening edges of dough if necessary. Spoon beef filling over long half of dough, leaving 1-inch border on 3 sides. Gently lift and pull top half of dough over filling to enclose; pinch dough edges to seal.
Bake in 400°F oven 15 to 20 minutes or until crust is golden brown. Cool 5 minutes. Cut crosswise into 8 slices.