Take out the pizza dough and set it on the counter to warm up a little while you prepare the pizza toppings.
Preheat the oven to 450°F. Oil your pizza or baking pan.
Slice the Polish sausage into thin round slices, then sauté it in a pan until it is slightly crispy.
While the sausage is cooking, thinly slice the peppers and onion.
Remove the sausage from the pan and set it aside, then cook the peppers and onion in 1 tablespoon of olive oil in the same pan.
Stretch out the pizza dough with your hands to the edges of the pan. Par-bake the dough for 7 minutes.
Once the dough is par-baked, remove it from the oven and spread the mustard evenly over the dough. Then place the pepper and onions over the mustard.
Add the sausage to the pizza. Space the slices out evenly.
Sprinkle the asiago cheese and then top with the mozzarella cheese over the pizza. Bake for 8 minutes. The pizza is done when the cheeses are melted, and the edges of the crust are slightly browned.