Wrap tortillas in damp paper towels and then in aluminum foil. Bake at 350° for 7 minutes or until softened; set aside. Coat a large nonstick skillet with cooking spray; place over medium-high heat until hot. Add chicken, chili powder, and cumin; saute 5 minutes or until chicken is done. Combine chicken, pepper, salt, and lime juice in a bowl, and toss well. Add, green onions, cilantro, and yogurt, and toss well. Place a lettuce leaf on each tortilla; divide chicken mixture evenly over lettuce. Top each with 4 tomato pieces; roll up. Yield: 4 servings. Nutritional value per serving: Calories 284 (18% from fat), protein 31.4g, Fat 5.8g (Sat 1.5g, Mono 2. 1g, Poly 1.4g), Carb 27.7g, Fiber 2.4g, Chol 73mg, iron 2.7mg, Sodium 248mg, calcium 125mg chick 67