In a mixing bowl, add grated potatoes, salt and egg. Add flour, mixing well. Add water if dough is stiff. Drop dough from moistened spoon into a kettle of boiling water. Cook partly covered for 7 to 10 minutes, stirring occasionaly. Drain and rinse with cold water.
In skillet, saute onions in butter/margarine until golden brown. Add grated cabbage and salt. Cover and fry over low heat stirring occasionaly until tender and golden brown. Add to dumplings, mix well. You may need to add more salt to your taste.