Cook 2 medium-sized sweet potatoes in the oven, in a pot of boiling water, or in the microwave until they are tender and done. Let it cool and then peel it.
Refrigerate the 1/2 cup Crisco and 1/2 cup water. It is important that these two ingredients are cold. You will get a crust that is flaky and tender.
Add flour and salt to a mixing bowl and combine well. Add the shortening and mix it in with a fork. Add the cold water and stir until the flour absorbs it. Put down the fork and start mixing with your hands until it sticks together.
Shape the dough into a large ball and knead a few times. Sprinkle cornstarch or flour on the surface before placing the dough to prevent it from sticking. Make two equal portions of dough and set them aside.
Spread flour or cornstarch onto your rolling pin and roll out one-half of the dough to about 1/8" thickness. Cut into four-inch circles, similar to a large bologna slice.
Once you've got scraps left, knead it just long enough to get it to stick together and repeat. Each half of the dough should yield 9 rounds. Repeat the process with the other half of the dough. cover the rounds with a kitchen towel or paper towel and place them on a cookie sheet.
Mix the two cooked and peeled sweet potatoes together with a wooden spoon. Mix in the sugar, cinnamon, and melted butter.
Place a heaping tablespoon of mixture in the center of a pastry round. Make sure you don't use too much filling, as it may leak out once it's folded over.
Press your fingers together to seal the fold. Secure the seal with a fork by gently pressing it. They also have that cute little design as a result.
In a skillet, heat shortening or oil and carefully place a few jacks, being careful not to crowd them. Cook each side until golden brown.
Remove and drain excess oil on a lined cookie sheet. If you wish, you can dust them lightly with powdered sugar. Enjoy!