For pastry shell, in a medium mixing bowl stir together all-purpose flour and salt. In a 1-cup measure combine the 1/4 cup skim milk and cooking oil. Add oil mixture all at once to flour mixture. Stir with a fork until dough forms a ball. On a lightly floured surface flatten the ball of dough with your hands. Roll out from the center to the edge, forming a 12-inch circle.
Ease pastry into a 9-1/2- or 10-inch tart pan with a removable bottom, being careful not to stretch the pastry. Trim pastry even with rim of pan. Do not prick. Line pastry with a double thickness of heavy foil. Bake in a 450 degree F. oven for 10 to 12 minutes or until edge is golden. Remove from oven. Reduce oven temperature to 325 degrees F.
Meanwhile, in a medium mixing bowl beat eggs slightly with an electric mixer. Add ricotta cheese, goat cheese, and the 1/4 cup milk. Beat until smooth. Stir in spinach, roasted sweet peppers, and the fresh or dried oregano. Pour egg mixture into pastry. Bake in a 325 degree F. oven about 20 minutes or until a knife inserted near the center comes out clean.
Let stand 5 minutes. If desired, top with sweet pepper strips and additional fresh oregano. Makes 12 appetizer servings.