Blend shortening into sifted dry ingredients. Combine egg yolks with potatoes. Add to dry ingredients. Add yeast to cooled milk. Gradually blend into other mixture. Let rise for 40 minutes. Cut and let rise again. Roll dough 3/8-inch thick. Fry in hot fat. Glaze.
Add 3 tablespoons water to 1 cup powdered sugar. Dip donuts into mixture.