In a large bowl, weigh and add all ingredients. Add the sourdough starter and knead on medium-low in your mixer for 8 minutes. If you are using your hands for kneading, knead for 10 to 12 minutes. No matter how you end up kneading, your goal is to be left with a fairly smooth dough. 

Add the dough to a lightly oiled bowl and let the dough rise for 1.5 to 2 hours in a warm spot in your kitchen.

Once your dough has doubled in size, divide it into 10 to 12 similarly sized dough portions. If you decide to go with 10 muffins, you will have larger sandwiches, and 12 dough portions will lead to muffins that are a little bit smaller. 

Once you have all of your dough portions portioned out, on a lightly floured work surface, turn all of your dough portions into balls. Cover all of your dough balls with plastic wrap or a clean towel so they don't dry out, and let them rest for 15 minutes. 

After fifteen minutes, flatten each dough ball into a flat circle and place each flat dough circle on a semolina flour or cornmeal-dusted sheet pan. I prefer semolina, but cornmeal works too. Once all of your dough circles are on your sheet pans, sprinkle the top of each one with semolina or cornmeal. Cover your sheet pans with lightly greased plastic wrap or a second upside-down sheet pan and let the dough rise for 30 to 45 minutes. 

After 30 or 45 minutes, your muffins should have risen a little, but not doubled. Heat a griddle or large pan over low heat. After your griddle or pan has been heating for 4 or 5 minutes, you're ready to cook. 

Very carefully, one at a time, move your risen English muffins from your sheet pan to the griddle. You want to do this very carefully so that you do not deflate all of the air pockets that the yeast has created during the final rise time. I like to use a spatula and slide them from the sheet pan to the griddle. Do not flip over from the sheet pan to the griddle/pan at this point because that will definitely deflate them. 

Cook each English muffin on low heat for 7-ish minutes a side. Be careful when flipping because you can still deflate the muffin during the first flip. Keep the heat down low, and you should be able to slowly cook these to a golden brown color. 

Cook each English muffin until it is golden brown on both sides. Depending on the heat of your stovetop, this might take more or less time than 7 minutes. Just keep a close eye on things. 

If any of the muffins are browning too quickly, remove that English muffin and cook it on a sheet pan in a 350-degree oven for 5 to 10 minutes until the interior is 200 degrees. 

Once all English muffins have been cooked, move them to a wire rack to cool. When they have had adequate time to cool (at least 1 hour), move them to a covered container or bread bag and store in a cool place for up to a week. 

Before serving, make sure to poke a fork into the sides of a muffin over and over to split it. This helps to create the nooks and crannies that you expect in an English muffin.