Place all of the ingredients into the bowl of a stand mixer. Give it a brief stir with a whisk or wooden spoon to make a shaggy dough. Attach to the base of the stand mixer and fit with the dough hook. Knead on medium-low speed for 8 minutes. Cover and allow to ferment and rise for 6–8 hours, or until doubled in bulk.Preheat a cast iron skillet over high heat. If you have 2 cast iron skillets, get them both going to cut down on cooking time.Place the risen dough onto a well-floured work surface. Form into 12-16 balls, depending on how large you want the final naan to be. Roll each ball into a circle that's 1/8-inch thick and about 6 inches across. Place a circle of dough onto the preheated skillet. Cook for 2 minutes, or until the bottom is deeply browned. Flip and cook for 2 more minutes, or until the bottom is very dark (almost black) in places. Remove to a plate and repeat with the remaining dough.Serve warm or at room temperature. Note: An active sourdough starter is one that has been fed 8–12 hours previously and is active and bubbly. I keep my sourdough starter at 100% hydration, which means I feed it equal weights (not volumes) of water and flour.