Sauté onions in oil and add paprika and dilute with a little water then simmer covered for 15 minutes. Drain and keep the liquid. Mix onions with egg, flour and a pinch of salt and pepper. Work into a soft dough (add water if necessary). Add reserved liquid to water to make 4 cups of broth. Add salt and bring to boil. Make small dumplings (1") and add to boiling broth and cook till dumplings are done. Mix sour cream and yolk together and put in tureen and ladle soup little by little while constantly stirring to prevent curdling. Heat and serve.