Heat oven to 400. Coat a pizza pan or a baking sheet w/ a little olive oil, sprinkle w/ a little cornmeal. ( it helps keep the pizza from getting too soggy.)
In lg skillet, over medium-high heat, Cook chicken in oil for 5 mins, turning chicken over once. Remove chicken from pan. Add red bell pepper and onion to pan. Saute 5 mins.
Unroll pizza dough onto pizza pan, press to form a 12" x 8" rectangle. Pinch edges to form a crust. Spread taco sauce onto dough. Top w/ chicken and veggies. Sprinkle w/ cheese. Bake 13-18 mins, or until crust is lightly browned and cheese is melted.