1 lb Sirloin steak; thin strips 1 1/2 ts Chili powder 3/4 ts Salt 3/4 ts Pepper 2 tb Vegetable oil 1 Onion; in strips 4 Cloves garlic; minced 1 ts Ground cumin 1 pn Hot pepper flakes 1 Sweet red pepper 1 Sweet yellow pepper 1 Sweet green pepper 1 Zucchini 1 ts Dijon mustard 2 tb Fresh coriander; chopped 10-inch tortillas 2 Avocados 1/3 c Lime juice