Combine yeast and water in large mixing bowl, stirring until dissolved. Add salt and 3 cups flour and beat until smooth. Blend in dissolved baking soda thoroughly. Beat egg whites until softly stiff and fold into the batter. Gradually add sufficient flour to make a soft workable dough that pulls away from the sides of the bowl. Turn out on floured surface and knead about 5 minutes. Round dough into a ball and place in a warm bowl brushed with melted shortening or butter, turning to coat the top. Cover loosely with plastic wrap and a towel and let rise until doubled - about an hour.

Punch down the dough, knead lightly, cover and let rest 10 minutes. Roll out the dough 3/8 inch thick. Cut out muffins with a 3-inch round biscuit cutter. Sprinkle a sheet of wax paper with white cornmeal. Place muffins on the paper and sprinkle tops with more cornmeal. Cover and let rise 45 minutes.

Bake the muffins on an ungreased griddle over moderate heat, about 8 minutes for each side. It may take longer; keep a close check to see that they do not burn. Remove to wire racks and cool, then split with a fork, toast and serve with loads of butter and strawberry jam. Freeze any leftover muffins.