Mix melted butter, starter, and water in a large mixing bowl. Add flour and salt and continue mixing until you have a soft, slightly sticky dough. Dump onto a lightly floured surface and knead for a minute or two. Cover and let rest for 30 minutes.
Divide dough into 12 equal pieces and roll each piece into a ball. Cover the dough balls. Roll each ball as thin as possible. Roll from the center out to the edges in a circular motion to keep the tortilla round. You are looking for somewhere between 9-10 inches across. Many recipes will tell you to use flour when rolling but I think this makes it very hard to get a thin tortilla. The stickiness can actually help to get the dough really thin. I roll mine out on a marble pastry board or straight on my soapstone countertops. If you find them sticking you can use a tiny bit of oil rather than flour.
Preheat a dry skillet, preferably cast iron, over high heat. Cook each tortillas for about 30 seconds per side. If you have a large griddle you can cook 2 at a time. They are ready to flip when they have bubbled up and you see some brown spots on the underside. This happens very fast so don't walk away.
Place cooked tortillas in a kitchen towel. Repeat until all tortillas are cooked.
