Soften yeast in lukewarm water, add sugar and salt. Add 1 cup of flour and beat vigorously; add melted shortening, egg whites, and blend well. Add remaining flour and mix well.
Place dough on floured board and knead until smooth and elastic. Place dough in greased bowl, cover and let rise until double in bulk. Punch down. Let rise again until light, then knead a few times.
Divide into 24 portions for rols. Cover and let stand for 10 minutes. Shape into buns or vienna rolls. Brush tops with water or milk, dip tops into sesame seeds. Place on greased baking sheet sprinkled with corn meal.
Cover and let rise until double in bulk. Bake in 450°F oven for about 18 minutes. Place a flat pan filled with boiling water in the bottom of the oven to give steam, which makes the rolls crusty.