Combine the flour, sugar, and salt in a large bowl. Add 1/2 cup of the warm water, then mix remaining 1/2 cup water with the yeast until foamy; stir into the flour mixture. Stir the flour mixture until moistened, then turn out onto a lightly floured surface and knead for 5 minutes, adding more flour if needed to keep the dough from becoming sticky. Lightly oil the bowl you mixed the flour in, then place the dough back in the bowl, cover with a clean kitchen towel, and let rise for 1 hour.
While the dough rises, prepare the sauce. Put the undrained tomatoes in a bowl and crush with your hands, then add the very thinly sliced onions and sugar and stir. Set aside.
Coat a 17x11 inch or slightly larger baking sheet with the olive oil, adding more if necessary to thickly coat the sides and bottom.
Punch the dough down and hand stretch it as much as possible. Place on the baking sheet and continue to press the dough down until it covers the sheet. The olive oil should have spilled over the top and covered the entire top of the dough, if it doesn't brush with additional. Let rise again for 15 minutes.
Preheat oven to 400 degrees F
Sprinkle half of the cheese over the top of the dough, then spoon the sauce/onion mixture on top. Sprinkle with remaining cheese, oregano, and black pepper.
Bake in the preheated oven for 20-25 minutes until the crust is golden brown.