Six hours or so before starting your dough, feed your sourdough starter equal parts flour and water. Once the starter has doubled in size, it is ready to use.
In a large bowl, add the water, starter, milk, salt, and honey. I find that this recipe is the easiest if you use a food scale and add the ingredients by weight.
Stir with a whisk until all ingredients are combined. Do not overmix.
Add the flour and baking soda. Using a whisk, mix until the flour is incorporated. This will take a few minutes.
In the bowl, or on a flat surface, knead the dough lightly for 3-5 minutes or until a dough ball has formed and there is no visible flour left on the dough.
Place the dough ball back in the bowl and cover with plastic wrap.
Let the dough ferment at room temperature overnight or for 8–12 hours.
Once the dough has fermented, place it on a clean surface sprinkled with cornmeal. Flatten/stretch the dough gently to about ½” thick.
Using a cup edge, or biscuit cutter, cut out the English muffins. (Mine were about 3” in diameter.) Roll up the dough scraps and flatten them back out to form the remaining muffins.
Sprinkle cornmeal on the other side of the dough, and let the muffins rest on a baking sheet for one hour at room temperature, or in the oven with the light on. Cover with a tea towel while they rest.