1. Preheat oven to 450°F. Coat a large baking sheet with cooking spray.
2. Divide dough into two equal portions. On a lightly floured surface, roll dough into two 10-inch circles. Transfer circles to prepared baking sheet. Set aside.
3. Whisk together sour cream, mustard, oregano and black pepper. Spread mixture all over both circles, to within 1 inch of edges. Top one half of each circle with half each of ham and cheese. Lift untopped side of dough and fold over filling so it meets other side, forming a half moon. Pinch edges together to seal. Coat surface of calzones with cooking spray.
4. Bake until puffed up and golden brown, about 25 to 30 minutes. Let stand 5 minutes. Slice each calzone into thirds. Yields 1/3 calzone per serving.