1. Combine the crab meat, peppers, scallions, and oregano in a medium-sized bowl. Add the mayonnaise and sour cream, and stir to mix well. Set aside.
2. Slice each roll crosswise into 12 (1/2-inch) slices. Arrange the slices on a baking sheet, and bake at 300°F for 15 minutes, or until lightly browned and crisp.
3. Spread each slice with 1 1/2 teaspoons of the crab meat mixture, and top with 1/4 teaspoon of the Parmesan cheese. Increase the oven temperature to 400°F, and return the appetizers to the oven for 5 minutes, or until the Parmesan is lightly browned.