Preheat oven to 425°.
Unroll pizza dough onto a large baking sheet coated with cooking spray; fold under edges of dough to form an 11-inch circle. Bake at 425° for 7 minutes; set aside.
Increase oven temperature to 475°.
Heat olive oil in a medium nonstick skillet over medium-high heat. Add bell pepper, and sauté 1 minute. Add 2 tablespoons water; cover, reduce heat to low, and cook 10 minutes or until bell pepper is soft. Spread tomatoes over dough, leaving a 1/2-inch border around outer edge, and top with bell pepper and mushrooms. Sprinkle with dried oregano and kosher salt. Bake pizza at 475° for 12 minutes. Top with cheese, and bake pizza an additional 3 minutes or until cheese is melted.