Heat olive oil in a small pan and saute onions until translucent
Add diced tomatoes, oregano, and basil to the onions and heat until just before boiling
Add balsamic vinegar and mix well
Add enough tomato paste to thicken the sauce
Set the sauce aside to cool
Mix sugar, yeast and 10 ounces water (about 100 degrees) in a bowl and let bloom for 15 minutes.
Combine flour, salt and cream of tartar in the bowl of a stand mixer. Once yeast has finished, add it to the dry ingredients along with the oil. Gently combine with a spatula until a rough ball is formed.
Knead in kitchen mixer on low speed with a dough hook for about a minute and a half. Don't over knead. If you don't have a kitchen mixer, knead on a floured surface with floured hands for about 2-3 minutes.
Transfer the dough to a lightly oiled bowl and cover with a tea towel until doubled in size, about 6 hours. Punch down and let dough settle for about 15 minutes.
Preheat to 450 degrees F
Coat bottom and sides of a 12-inch cake pan or traditional Chicago style pizza pan with the melted butter. This will help the pizza release from the pan and have a nice crispy outside crust. Save a little bit of the butter to put on top of the edge crust. I prefer a 12-inch spring pan to easily release the whole pie.
Using your hands, spread the dough across the bottom and up the sides of the pan. If the dough is loose don't worry about it. Make sure the edges come up the sides of the pan. brush the remaining butter on the top edge of the dough
Create a layer of mozzarella on the bottom of the pan all the way up to the edge. If the dough is loose use the cheese to define a bottom layer.
Remove casings from the sausage links. Cut two pieces of parchment paper at least 12x12 inches. Spread the sausage into an 11 inch circle on one of the parchments. Cover with the other parchment and smooth the sausage into a large patty
Peal away the parchment and press the sausage patty onto the cheese
Top with a ladle of the sauce. Sprinkle top lightly with grated Parmesan cheese
Bake for 25-30 minutes until the top edge of the crust is golden brown. Rotate the pizza about 12 minutes after baking starts.
Let the pizza cool for at least 5 minutes before serving