Line 2 sheet pans with parchment paper and dust generously with fine-ground cornmeal, covering the parchment completely, and set aside. Cover a work surface with a generous dusting of all-purpose flour and tip the chilled dough onto the work surface, dusting the top of the dough with more flour. Use a bench scraper to divide the dough into 12 equal pieces around 3 ounces each.
Dust your hands generously with flour. Working with 1 piece at a time, fold the dough inward on itself four times, folding each corner of the dough towards the center to form a rough ball. Turn dough over so that the folds are underneath the dough ball and transfer to the prepared sheet pan. Repeat with remaining dough, spacing each dough ball evenly on the sheet pans.
Sprinkle the top of each dough ball with cornmeal. Cover each sheet pan with a loose sheet of plastic wrap and let sit at room temperature until the dough looks puffy and airy, around 1 to 1 1/2 hours.
Toward the end of the muffins' rise time, prepare your cooking area. Center a rack in the oven and preheat to 350 (F). Heat a large cast iron skillet pan over medium heat. Melt a small pat of butter in the pan — just enough to coat the bottom and sides, and no more — and swirl the cast iron skillet. Brush the inside of 3 English muffin rings with vegetable oil and place them in the pan, allowing an inch or so of space between each ring — avoid crowding the pan since you'll need space to flip each ring over.
Transfer each dough ball to the inside of an English muffin ring by sliding 2 thin metal spatulas from opposite sides underneath each dough ball, getting underneath the cornmeal to avoid accidentally sticking or deflating the dough. Cook until the bottoms are dark golden brown, around 5 to 7 minutes, and use a metal spatula to flip each muffin (still in their rings) to cook until the other side is dark golden brown, around 5 to 7 minutes. When done, transfer the English muffins to a parchment lined sheet pan and carefully pop them out of their rings — be careful, the rings will be hot! Transfer to the preheated oven and bake for 10 to 15 minutes, or until a digital food thermometer inserted into the center of each muffin reads between 200 and 215 (F). The muffins won't brown much more, but the interior will bake through. Transfer to a wire rack to cool 5 to 10 minutes before serving.
Repeat with the remaining dough balls, cleaning out the castiron skillet of any excess cornmeal before reheating.
Once the English muffins are done, slice the herb-cured steelhead as finely as you can at an angle. There's no need to rinse off the second cure; simply serve with the homemade English muffins, with cream cheese, crème fraîche, and lemon.