Wrap tortillas in foil. Place in a 300∞ oven for 10 to 12 minutes or till heated through.
Meanwhile, spray a large skillet with nonstick spray coating. Add onion and garlic; stir-fry for 2 minutes. Add red pepper; stir-fry for 1 to 2 minutes more or till vegetables are crisp-tender. Remove from skillet. Add oil to skillet. Add chicken; stir-fry 3 to 5 minutes or till chicken is tender and no longer pink. Return vegetables to skillet. Add salsa. Cook and stir till heated through.
To serve, divide chicken mixture evenly among tortillas. Top with shredded lettuce. Dollop with yogurt and sprinkle with green onion. Roll up tortillas.