Here is the recipe I used recently. I made a note that mine took only 6-7 minutes per side to bake on a lightly greased cast iron griddle.

Sourdough English Muffins by Dean Tucker, "Sourdough Cookin'"

1 cup sourdough starter

2 1/2 cups unbleached bread flour

3/4 cup buttermilk

1/4 cup yellow cornmeal

1 t. baking soda

1/2 t. salt

Take buttermilk and starter from refrigerator at least 30 minutes before preparing recipe.

When all ingredients are at room temp, combine and stir well. Turn dough onto a lightly floured board or work surface and knead until smooth or knead about 5 minutes in a heavy duty mixer such as a Kitchen Aid or Bosch, adding a little more flour if necessary.

Roll dough to 1/2-inch thickness and allow to rest for 10 minutes. Cut with a floured 3 or 4-inch round floured biscuit cutter. You can use a very clean tuna can with both ends cut out if need be. Sprinkle 2 TB cornmeal on a sheet of waxed paper. Place muffins on cornmeal and press lightly to coat each side.

Cover with plastic wrap and a clean towel and let rise for 1 hour. Cook muffins on a lightly greased griddle heated to 350 for 20 minutes (or less-see my note), turning occasionally while cooking.

When done, split and butter and toast, then spread with honey or your favorite jam, jelly, or cream cheese.

Recipe makes 10-12 muffins.

Note #2: you can sub 1 cup whole wheat flour for 1 cup of the unbleached if you want whole wheat muffins.