In a one-gallon saucepot heat one quart of vegetable oil to 350 degrees F.
To make the dough, mix the flour, salt, and sugar together and cut in the margarine by hand to create a coarse cornmeal texture. Then add the water until it is tacky. Roll the dough into a ball. Cut dough into ten equal pieces. Roll each piece of dough out on a floured surface to a diameter of 6-inches and about 1/8-inch thick. Set aside until you are ready to fill the dough.
To make the filling, first peel the sweet potatoes. Then large dice the potatoes and put in a medium size saucepot. Add water to cover potatoes and bring to boil. Potatoes are done when fork tender.
When sweet potatoes are finished boiling, drain well. In a food processor, while still hot, add the potatoes, margarine, cinnamon, nutmeg, vanilla, and sugar. Mix on medium speed until smooth.
To assemble pies, put 1/4 cup of the filling in the center of a dough circle. Fold over in half and seal with water. Crimp edges with a fork to completely close. Place pies in oil once the temperature has reached 350 degrees F. (If temperature is below 350 degrees F the oil will absorb the margarine in the pie dough and cause it to be excessively greasy.) Pie should be cooked in 7 to 8 minutes and will have a golden brown color.
Recipe courtesy of Charles "Chucky" Gammon, Chuckies Fried Pies, Memphis, Tennessee