Heat oil in a large nonstick skillet over medium high heat. Add chicken and pepper; sautee until chicken is golden on all sides, about 5 minutes. Stir in salsa, rice, and chili powder. Bring to a boil, reduce heat, and simmer about 5min, stirring occassionally. Remove from heat; stire in cheese until melted. Divide mixture between tortillas. Fold up, making sure ends are securely tucked in (use toothpicks if necessary). Place in a sprayed 9x13 pan. Bake uncovered at 350 or until tortillas are crisp and brown, about 20 minutes. Serve topped with sour cream, additionaly salsa, and lettuce if desired.