Cook potatoes, onion in 1/2 cup water. Drain sauerkraut and chop hot dogs. Add sauerkraut and hot dogs to mixture and cook for 20 minutes or until potatoes are tender. Gradually add bread crumbs until mixture is moist and thick. Add mustard powder and caraway seeds and pour mixture into uncooked pie crust. Place 2nd crust on top. Prick the top crust and brush with milk. Bake at 350 degrees for 1 hour.