Add 1.5 cups of sourdough starter discard to a glass measuring cup. If it isn't already a pancake batter consistency, add just enough water to bring it to the desired consistency. The batter needs to be pourable but not runny.
Heat the cast iron skillet over medium heat until it is smoking, then lower to medium-low and add enough oil to evenly cover the skillet (~1 Tablespoon). Once shimmering, it's time to add the "dough" batter.
Pour the sourdough batter into the skillet in a circular motion and immediately evenly disperse it with a spatula. (tip: if you prefer a thicker crust, add more batter or keep a thicker consistency in step #1).
Once the batter is bubbling (just like pancakes do) flip the crust over.
Add your favorite pizza toppings (sauce, meat, vegetables/fruit + cheese)
Turn the oven on to a high broil.
Add the pizza to the prepared oven for 5-8 minutes, or until the cheese begins to brown/bubble.
Remove and let rest for a few minutes (it will be very hot!) and enjoy!