In stand mixer bowl, add 1 杯 flour, yeast, sugar and 盐; mix well. Add sourdough starter, warm water and oil to flour mixture. Using a paddle attachment, blend on low speed for 30 seconds; beat on medium speed for 4 minutes.
Switch to dough hook attachment. Gradually stir in enough remaining flour to make a firm dough. Knead until smooth and elastic, about 5 to 7 minutes.(NOTE: For hand mixing: following above steps, mix ingredients in large mixing bowl using a wooden spoon or dough whisk. Knead on floured surface until smooth and elastic.)
Place dough in lightly oiled bowl and turn to grease top. Cover; let rise until indentation remains after poking dough with finger down to second knuckle, about 1 hour.
On surface dusted with cornmeal, roll dough to 1/4-inch thickness. Cut into 14 to 16 circles (3 to 4 inches in diameter). Turn to coat topside with cornmeal. Place on greased cookie sheet. Cover; let rise until indentation remains after touching.
Preheat griddle to 325°F.
Carefully place muffins on preheated electric griddle or fry pan. Bake 10 minutes on each side or until sides are deep golden brown. Cool on wire rack. To serve, split and toast.