Dissolve yeast in warm water
In a large bowl, mix together the yogurt and boiling water. Cool to lukewarm.
Stir in the yeast, then 4 cups whole wheat flour, and cover the bowl with a towel. Let this sit in a warm place until doubled in bulk.
After the dough has doubled in bulk (about 60 minutes), mix in the remaining flour, along with the salt and baking soda. Knead vigorously, adding more flour as needed until you have pliable but slightly sticky dough.
Return the dough to the bowl (I oil it slightly and turn the dough oil side up) and let rise a second time. This takes 30 minutes or more. Punch down and turn onto a floured surface. Roll it into 1/2" thickness. Cut into 4" circles.
Dust both sides of the muffins with cornmeal and place on cookie sheets to rise until double in bulk, about 45 minutes to 1 hour.
Cook in a medium (325) electric skillet or on a griddle for 20 minutes or until they look done, turning every 5 minutes. A heavy iron griddle over a medium burner will also work.
To make English muffin bread, grease two bread pans, then dust with cornmeal. Instead of shaping into muffins, place dough into loaf pans after second rise. Allow to rise the third time, until double in bulk. Bake 350 for about 30 minutes.