Crust: Dissolve sugar and yeast in warm water in a small bowl; let stand 5 minutes. Place flour, cornmeal, and salt in a food processor, and pulse 2 times or until blended. With processor on, slowly add yeast mixture and oil through food chute; process until dough forms a ball. Process for 1 additional minute. Turn dough out onto a lightly floured surface, and knead lightly 4 to 5 times. Place the dough in a bowl coated with cooking spray, turning dough to coat top. Cover the dough, and let rise in a warm place (85 degrees), free from drafts, 45 minutes or until doubled in bulk.
Heat 1 tablespoon oil in a large nonstick skillet over medium heat. Add bell pepper, onion and crushed garlic, and saute for 5 minutes. Add mushrooms, sausage dried oregano, and salt; saute 3 minutes or until tender. Remove from heat; let cool.
Punch dough down; cover and let rest for 5 minutes. Divide dough in half.
Roll each half of dough into an 11-inch circle on a lightly floured surface. Place the dough into 2 (9-inch) round cake pans coated with cooking spray and each sprinkled with 1 tablespoon cornmeal; press dough up sides of pan. Cover and let rise 20 minutes or until puffy.
Spread half of vegetable mixture over each prepared crust, and top each with half of the crushed tomatoes. Sprinkle cheeses evenly over pizzas. Bake at 475degrees F for 15 minutes. Reduce oven temperature to 375 degrees, and bake an additional 15 minutes. Cut each pizza into 8 wedges. Garnish with oregano sprigs, if desired.