Place flour and salt in a food processor bowl fitted with a metal cutting blade. Process until mixed. Add the 1/2 cup butter and the shortening; process with on/off turns until mixture is the consistency of coarse oatmeal. With the machine running, add 4 tablespoons of the ice water all at once. Watching the dough carefully, add remaining water 1 tablespoon at a time, until dough gathers into a ball. Remove dough from machine, and form into a ball. Wrap in plastic wrap, and let rest in refrigerator at least 1 hour.
Preheat oven to 425 degrees F. Roll dough on a floured surface, until 1/8 inch thick. Cut twenty-four 3-inch circles of dough. Press circles into ungreased 1-3/4-inch muffin cups. Do not prick. Bake in preheated oven for 6 to 7 minutes or until pastry cups just begin to brown. Remove from oven and reduce temperature to 350 degrees F.
For filling, cook mushrooms in the 1 tablespoon butter or margarine in a small saucepan over medium-high heat for 4 to 5 minutes or until most of the liquid has evaporated. Set aside to cool slightly. Lightly beat together egg, milk, and ground black pepper. Add cooked mushrooms, cheese, bacon, and chives or green onion.
Fill each pastry cup with about 1 teaspoon of the quiche filling. Return to oven; bake for 10 minutes or until filling is set. If desired, garnish with red pepper strips. Serve warm. Makes 24.