Add starter and water to a large bowl and stir until starter is dissolved. Allow to rest for 15 minutes uncovered on the counter.
To the starter mixture, add olive oil and flour. Stir until a shaggy ball and all of the flour is incorporated. Cover with plastic wrap and allow to rest for 30 minutes on the counter.
Stretch and Fold: Uncover the dough. Using your hands, reach under the dough and scoop the bottom to the top. Rotate the bowl 45 degrees and repeat the process. Do this a total of 8 times. Cover the dough with plastic wrap and allow it to rest for 30 minutes.
In a small bowl, add 2 Tbsp of water and salt and stir until dissolved. Add your salt water to the dough and continue to stretch and fold until water is incorporated. Be very gentle with your stretches and folds, make sure to allow the bubbles to form without being popped. Cover with plastic wrap and allow to rest on the counter for 30-60 mins.
If your dough seems too sticky to work with, you can add an additional 1/4 C flour and incorporate it in your stretching and folding. Now do your final stretch and fold until the dough feels stretchy and the gluten has developed. Cover your dough with plastic wrap and place in refrigerator for 12-24 hours.
Remove from the refrigerator and allow to warm up to room temperature on the counter for 2 hours before working with your dough.
Preheat your oven to 500 degrees. In a 9x13in sheet pan, add 2 Tbsp favorite oil and spread it around the pan. Add pizza dough to the pan and gently spread it out using your fingers to cover the pan. As the dough relaxes it will spread out naturally.
Add another 1-2 Tbsp olive oil on top of the dough and continue to spread it out. Spread your sour cream on top of the dough in an even layer. Then add your sliced onions on top of the dough. Break up your raw ground sausage and add on top, covering the entire surface. Now break up fresh mozzarella and add to top, covering the entire surface.
Add the dough to the oven and allow to cook for 15 mins. Pull the pizza partially out of the oven and add the grated parmesan cheese on top, then allow to cook for another 5 mins until golden brown. Let rest for 10 mins and then use kitchen scissors to cut slices. Enjoy!