About 2 pounds russet potatoes (approx. 6 medium potatoes)
2 cups all-purpose flour
1 large egg
1/2 tsp salt
1 Tbsp vegetable oil

1. Place the unpeeled potatoes in a large pot, add water to cover, and boil until fork-tender. While still warm, peel and rice or mash the potatoes. Let cool completely. Combine the potatoes, egg, 1 tablespoon oil, salt. Stir in the flour until the dough is no longer sticky and holds together. Now this is tricky: too much flour produces heavy dumplings - too little flour produces mushy dumplings.
2. On a lightly floured surface, knead the dough briefly until smooth. Do not overknead! Dust your hands with flour and shape the mixture into 1 inch balls. Flatten the balls into thin patties. Place a piece of a plum (below) or other filling in the center of each patty and press the edges together to enclose the filling. Reform into balls. I work about 5-6 dumplings at one time then boil in lightly salted water, stirring to prevent sticking and cook until dumplings rise to the surface (about 10 minutes), then repeat the process.