TO MAKE THE STARTER:

Combine 100 grams of the flour and 100 grams of room-temperature Altered water in a 2-quart wide-mouth Mason jar. Cover the opening with cloth and set aside at room temperature for two days.

Stir vigorously then dump out half of the contents of the jar. Feed the remaining starter by adding the remaining 100 grams of flour and 100 grams Altered water; stir to combine. Cover and set aside.

Repeat this process each day for 4 more days, or until the mixture is bubbly and active looking.

Use immediately or place the starter into the fridge for as long as one week. The starter will remain dormant for this time, and can be reawakened when brought to room temperature and fed.

TO MAKE THE ACTIVATED STARTER:

The night before making the dough (2 days before serving the English muffins), in a large bowl, combine I tablespoon of starter with the water and flour; Cover with a towel and let sit overnight at room temperature.

The next morning, the activated starter should be bubbly. To test whether it is ready to use, place a teaspoonful in a glass of water If the activated starter floats, you are ready to make your dough.

TO MAKE THE ENGLISH MUFFINS:

In a large bowl, mix together 350 grams room temperature Altered water and 100 grams of the activated starter. Add the all-purpose flour, rye flour, salt, and yeast; mix and knead until a fairly smooth dough forms, about 15 to 20 minutes by hand or 7 to 10 minutes in an electric mixer with a dough hook attachment.

Place the dough in a lightly oiled bowl. Cover with a clean towel, and allow to ferment at room temperature for 2 hours.

On a cutting board, divide the dough into eight equal pieces. Each piece should weigh about 110 to 115 grams. For each muffin, draw the edges of the dough toward the center to form a mound, then turn it over so the seam side is down; roll gently on the board with a cupped hand to make a smooth ball. Roll each ball in semolina flour; sesame seeds or poppy seeds, and transfer to a parchment-lined baking sheet. Cover loosely with a clean cloth and refrigerate overnight.

The next morning, preheat the oven to 400°F. Preheat an ungreased cast iron skillet on the stove over medium heat.

When the skillet is hot, brown the English muffins in batches of two or three by placing the raw dough onto the hot skillet and pressing down lightly to flatten. Allow the first side to brown slightly, about 3 minutes. Flip, press lightly, and allow the second side to form a golden brown crust, about 3 minutes.

Place the browned English muffins back onto the parchment-lined baking sheet. When all of the muffins have been browned, place the sheet pan in the oven and bake until the center of the English muffins finish cooking, about l2to 15 minutes.

Serve immediately or store for up to 3 days.