In a large bowl, dissolve sugar in water. Sprinkle yeast over water and let stand until foamy, about 5 minutes. Stir in 2 1/4 cups flour, cornmeal, salt, and 2 tablespoons oil and blend until mixture forms a dough. Knead dough on a floured surface, incorporating as much of remaining 1/4 cup flour as necessary to prevent dough from sticking, until smooth and elastic, about 5 minutes.
Put dough in a deep oiled bowl and turn to coat with oil. Let dough rise, covered with plastic wrap, in a warm place until doubled in bulk, about 1 hour.
While the dough is rising, in a heavy skillet cook sausage over moderately high heat, breaking up lumps, until no longer pink and stir in tomatoes, oregano, and salt and pepper. Transfer sausage mixture to a strainer over a bowl to drain and cool.
Preheat oven to 500 degrees F.
Punch down dough and knead 4 times. In an oiled 10 1/2-inch cast-iron skillet, press dough with oiled finger until it comes 2 inches up the side and is an even thickness on bottom. Let dough rise, covered loosely with plastic wrap, in a warm place for 15 minutes.
Sprinkle dough with half of mozzarella and fontina and top with sausage mixture and remaining cheeses. Sprinkle the top with the Parmesan and bake the pizza in the lower third of an electric oven, or on floor of a gas oven for 15 minutes. Reduce oven temperature to 400 degrees F. and bake 10 minutes more, or until crust is golden.
Recipe courtesy of Gourmet Magazine