Dissolve yeast in water and sugar. Let stand 10 minutes. Stir briskly and add to warm water, sugar, shortening, salt and vinegar. Beat in 6 cups flour, then knead in remaining flour for 10 minutes. Let rise in a greased bowl until doubled in bulk.
Punch dough down. Let rise 1 hour.
Preheat oven to 350 degrees.
Shape into buns, (3 small balls in muffin tins). Let rise 1 hour. Bake for 25 to 30 minutes.