Dissolve yeast in water. Sift flour with salt and sugar into a mixing bowl. Cut in shortening. Add buttermilk and dissolved yeast & mix well with wooden spoon. Transfer dough to well floured surface and knead a few seconds. Dough will still be sticky and soft. Put dough  in lightly greased bowl, turning to cover all of dough until lightly greased on surface. Then cover bowl with plastic wrap and let rise in warm place until doubled- about 1 hour. Turn dough onto lightly floured surface. Roll out into a rectangle, about 14x22" & 1/4" thick. Use 2" biscuit cutter to cut out 40 rounds or as many as possible. Don't re-roll scraps. Lightly dip each side in melted butter and fold to center, punching sides. Arrange rolls side by side, touching on a greased cookie sheet. Cover with plastic wrap. Let rise until double (approximately 45 - 50 minutes). Preheat oven to 400ºF. Bake in middle of oven for 5 minutes, reduce heat to 375F. for 15 to 20 minutes.