Feed your sourdough discard and wait for it to become active. Perform a float test to make sure that your discard is active and ready.
In a large bowl, combine your active sourdough starter with only 2 cups of the flour and water (reserve the remaining cup of flour for the morning). What you have created is called a poolish or levain. Cover the bowl with plastic wrap and allow it to sit on the counter overnight (or 7-10 hours).
In the morning, prepare a rimmed baking sheet by sprinkling it with half of the cornmeal.
Mix the baking soda, salt, and sugar into the dough.
Using 2 TBSP at a time, mix in the remaining 1 cup of flour, until the dough is no longer sticky.
Turn the dough out onto a lightly floured surface and roll to a 1/2" thickness. If you make them too thick, they won't cook all the way through.
Using a 3" biscuit cutter, cut as many rounds as you can. You can reform the dough scraps back together and cut more, but be careful not to overwork your dough or your english muffins won't turn out right. You should just be able to get twelve.
Place the english muffin rounds onto the prepared baking sheet and lightly dust the tops with more cornmeal.
Cover the english muffins with a clean kitchen towel and allow to rest for 45 minutes. They won't rise much at this time. That is ok, the magic will happen when you start to cook them.
Heat a lightly oiled skillet over medium high heat.
Place an English muffin on the skillet and cook for 3-5 minutes, or until the bottom is light-medium brown.
Flip over and cook for 3-5 minutes on the other side, until both sides are golden brown and the sides of the english muffin are dry. You can cook more than one muffin at a time, but do not crowd the skillet. Only do 2 or 3 at a time.
Allow to cool and enjoy!
Notes
Tips for making sourdough english muffins: Oil – You want the griddle lightly oiled, not swimming in it. Griddle – don’t heat your griddle too hot. If it is too hot, the bottoms will get too browned before the middle cooks all the way.How to store - These store best at room temperature for 1-2 days. If you are going to take longer than that to eat all of them, you can store them in a covered container in the fridge for 3-4 days.Can you freeze them? Yes, these english muffins freeze well! Allow them to cool completely, and then freeze them individually. I prefer to freeze them pre-split, but you can do what feels right to you. Make sure to label them so you remember what they are. Thaw them and rewarm in the oven or toaster, not the microwave.