Lay chicken in the bottom of the crockpot and top with taco seasoning.
Cut, chop, dice (whatever you fancy) the carrots, celery, and onion and add to the crockpot.
Add tomatoes, salsa, and water.
Cover and cook on low for 8 hours or, really, however long you want at whatever temperature you want so long as the chicken cooks!
When done, shred the chicken (still in the crockpot) with 2 forks. Add sour cream and mix well.
Serve