When the oil begins to smoke lightly, turn heat off and add 1 of the pizza rounds. Use a spatula to press gently on the top of the round to keep it relatively flat as it cooks. When you see it is slightly brown on the underside, season the top lightly with salt and pepper and flip the round on its second side. Season it with salt and pepper and top with the onion sausage-onion mixture and place the skillet in the center of the oven until the pizza has finished cooking, 5 to 8 minutes. Repeat with remaining dough and topping.