Toss chicken, carrots, celery, onion, garlic, tomatoes, potatoes, chicken stock, tomato paste, wine, fennel seeds, salt and rosemary into the slow cooker.
Cook on the lowest setting for 4-6 hours.
During the last 30 minutes of cook time, combine the corn starch with the water and mix until no lumps remain and add to the slow cooker along with the balsamic vinegar.
Turn heat to high, and cook for 30 additional minutes, until slightly thickened.
Transfer chicken thighs to a clean bowl and shred with two forks or an electric hand mixer. Return to the stew and mix in.
Remove the rosemary and serve.
In a heavy-duty gallon sized freezer bag, combine all ingredients except the water/cornstarch/balsamic vinegar.
Remove as much air as possible and freeze for up to 3 months.
Thaw completely before cooking as directed above.