Grate potatoes. Measure and sift flour. Measure butter. Soak sugar lumps in brandy. Remove stone of whole apricots. Measure bread crumbs, sugar and brandy. Measure ingredients for sauce. Mix flour with grated potato, add salt and egg yolk. Rub in butter and then turn dough out onto a floured board and knead. Press out dough to 1/4-inch thick. Place a lump of brandied sugar in each half apricot, cover with another apricot half. Cut dough into 4-inch squares. Place apricot in the center and wrap dough around, squeezing edges of dough together. Trim off outside. Roll dumpling between palms of hands. Drop dumplings into a large saucepan of salted boiling water. Boil gently for 12 minutes. Remove with slotted spoon and drain. Fry the bread crumbs with the sugar and 3 tablespoons fresh butter until crisp. Roll the dumplings in the bread crumbs and sprinkle with cinnamon. Place onto a heated serving dish. Coat with apricot sauce. Serve remaining sauce separately. Sauce: Place apricot halves with brandy and apricot juice into a blender and puree. Heat gently in a saucepan.