Preheat the oven to 400°. Coat each cast iron pan with oil. Place the coated cast iron pan in the oven for 10 minutes.
Take the pan out of the oven(wear oven mittens), spread thinly/evenly 1 cup each of the sourdough discard onto the pan. Sprinkle dried herbs seasoning. Put the pans back into the oven for 8-to minutes.
Spread the pizza sauce.
Then the cheese.
Then the pepperoni slices.
Put the pans back into the oven to cook for 8-to minutes. Or less, depending on how hot your oven is. Just keep an eye out so the crust don't burn.
VOILA! Sourdough Discard Pepperoni Pizza!