Brush both sides of tortillas with vegetable oil; cut into strips 1/2" wide. Arrange in single layer on a rimmed baking sheet; sprinkle with salt. Bake in a preheated 425° oven until crisp and golden-brown (5-6 min.); set aside. In a large stockpot, combine stock, tomatoes, chicken, onion, garlic, chili powder and cumin. Bring to a boil over medium heat; reduce heat and simmer until chicken is cooked through (15-20 min.). Break several tortilla strips into bottom of each serving bowl; cover with soup. Sprinkle with cheese, avocado and cilantro. Top with remaining tortilla strips and garnish with lime wedges.