To Make Dough: In a medium bowl combine the flour, salt, egg and water. Mix all together to form dough; cover bowl and set aside.
To Make Potato Filling: Place potatoes in a large pot. Add water to cover, bring to a boil, and boil for 25 to 35 minutes or until tender. Remove potatoes from water and mash. Place bacon in a large, deep skillet. Cook over medium high heat until evenly brown. Drain, crumble and stir into mashed potatoes. Stir in cheese and season with salt and pepper.
To Make Sauerkraut Filling: Place bacon in a large, deep skillet. Cook over medium high heat until evenly brown. Drain, crumble and place in a medium bowl. Stir in sauerkraut, then sour cream. Mix well.
Roll reserved dough out on a floured surface. Cut circles out of dough, using a small round container. Place a spoonful of potato or sauerkraut filling in the center of each circle and fold over, pinching edges together to seal. Bring a large pot of lightly salted water to a boil; drop perogies in boiling water and cook for 4 to 5 minutes, or until they float.
