In the crock of the slow cooker, pour the water (or broth). Whisk in the gravy mix, condensed soup, and minced garlic until smooth.
Use salt and pepper to season the chicken breast on both sides. Push the chicken into the gravy mixture. (use medium size breasts, if very thick slice them in half lengthwise so they aren't as thick)
Cover the slow cooker and cook on low for 6 hours. Remove the cover and use two forks to shred the chicken OR remove the chicken and dice with a knife. (if it is not really easy to shred with 2 forks it probably isn't done. It should pretty much fall apart when gently shredded. Thick breasts may need more time)
Stir the chicken and add the sour cream into the gravy. Serve over rice or egg noodles. Garnish with sliced green onions or parsley.