In a medium mixing bowl, whisk together sourdough starter, water, milk, olive oil, and honey. Mix in the remaining ingredients in the order they are listed. Then beat for several minutes with a wooden spoon or electronic mixer.
Cover dough and allow to sour for 8 to 18 hours.
When ready to bake, preheat oven to 450°F.
Line a 10-inch cast-iron skillet with parchment paper. Place half the dough in a parchment-lined pan. Spread it around with a spatula or wet fingers until completely even.
Very carefully remove parchment and dough from skillet and place skillet in oven to heat for 10 minutes. Carefully remove skillet, place dough back in pan, and return to oven to bake for 15 minutes or until firm around edges and in center. Top with your favorite toppings and return to oven for 10 to 15 minutes.