• In a large stand mixer, combine the water, instant yeast, bread flour, sourdough discard, and sea salt.
• Knead the dough on low speed for 6-7 minutes or until smooth and elastic.
• Cover the bowl and allow to rise for 2 hours.

Pizza Sauce

• Melt the butter in a saucepan over medium heat.
• Add the garlic and cook for 1 minute.
• Add the flour, whisking continuously for 3 minutes.
• Slowly add the milk, whisking continuously to prevent clumping.
• Add the horseradish sauce and season with salt and pepper.
• Bring the sauce to a simmer, whisking often for 5-10 minutes.
• Remove from the heat when thickened.

Steak, Onions, and Mushrooms

• Heat the grill to high heat.
• Season the steak with blackened seasoning.
• Grill the steak for 5 minutes per side. Remove the steak to a plate and cover with foil. Allow to rest while preparing the other ingredients.
• Heat 1 tbsp of butter over medium heat in a small cast iron skillet. Add the sliced yellow onion, stirring occasionally for 20 minutes or until caramelized. Remove the onions to a bowl.
• In the same skillet, melt 1 tbsp of butter. Add the sliced mushrooms and sauté until soft. Remove the mushrooms to a bowl.
• Preheat the oven to 425℉.
• Lightly flour a work surface and spread the pizza dough into a 16 inch circle.
• Place the dough on a floured pizza pan.
• Spread the sauce over the pizza, leaving 1 inch crust around the outer edges of the pizza.
• Sprinkle 1/2 cup of mozzarella on top of the sauce.
• Slice the flank steak into bite sized pieces and spread over the entire pizza.
• Add the caramelized onions and sautéed mushrooms.
• Add the remaining mozzarella, gorgonzola, and diced green onions to the pizza.
• Bake for 20 minutes, or until the bottom crust is cooked through and the top is hot, bubbly, and browning.
• Remove from the oven and allow to cool for 5 minutes before slicing.