In a slow-cooker, combine chicken breasts, ranch dressing mix, chicken broth, chili powder, cumin, and green chiles. Stir around until chicken is coated and there aren’t any big lumps of dressing mix.
Cover and cook on low for 4-6 hours or high 2-4 hour depending on how your crockpot cooks. Chicken should be cooked through and easily shred. Remove chicken from pot, shred, return to pot and stir in sour cream and chopped cilantro. Serve in tortillas with lettuce, cheese, avocado, and pico de gallo.