In a large mixing bowl, combine the flour and salt. In a separate bowl, stir together the sourdough starter, warm water, and olive oil.
Add the wet ingredients to the dry ingredients and mix until a dough forms, by using your hands or a dough whisk. You can also use a stand mixer fitted with a dough hook.
Turn the dough out onto a lightly floured surface and knead for several minutes, forming a smooth dough ball.
If doubling the recipe, use a dough scraper or knife to cut the dough in half.
Place the dough ball into a lightly oiled bowl and cover with a clean towel or plastic wrap.
Allow the dough to rise in a warm place for several hours, or until it has noticeably expanded. If using sourdough discard, it may not rise much.
Once the dough has sat or risen, roll it out on a lightly floured surface.
Meanwhile, place your cast iron skillet into the oven and preheat to 450°F.
Carefully remove the hot skillet from the oven using oven mitts. Transfer the dough into the skillet and gently press it to fit the bottom. Pinch around the edges to create a crust, being careful not to burn your hands (or you can use a spoon or fork to create the crust).
Brush the top lightly with olive oil, then sprinkle with garlic powder and oregano. Bake for 10 minutes.
Remove the crust from the oven and allow it to cool completely.
At this point, you can store the crust for later or immediately add toppings and finish baking.
When ready to serve, add your favorite sauce, cheese, and toppings. Bake at 350°F for about 10 minutes, or until the cheese is melted and bubbly.