Whip together the potatoes and oil, using wire whisk or fork. Mix together the flour, baking powder, and salt. Add the flour mixture to the potato mixture. Using a fork or your hands, blend the two mixtures together. do not over work.If the dough is too dry to hold together, gradually add a little water. (If your mashed potatoes are fairly moist you will not need to add any water. However, if they are dry, slowly sprinkle water onto the dough until it is moist enough to hold together.) Roll the dough out onto apiece of wax paper. Sprinkle the counter or tabletop with a few drops of water to keep the paper from slipping, and sprinkle the dough with flour to keepthe rolling pin from sticking. Pick up the dough by the edges of the paper and place it (paper side up) in a pie plate. Carefully peel off the paper. Flute the edges of the pie crust, fill and bake according to the recipe of your choice. From DEEANNE's recipe files