Add the chicken, celery and onion to the slow cooker.
In a small bowl whisk together the water, chicken bouillon cube, you may need to smash the chicken bouillon cube to get it to dissolve. Then whisk in the soy sauce, vinegar, cornstarch, pepper, ground ginger and garlic powder until smooth.
Pour this sauce over the chicken and veggies in the slow cooker.
Cover and cook on LOW for 6 hours. Serve over rice. Enjoy!
Freezer Meal Instructions:
Make the sauce as directed above, then let the sauce cool down in the fridge for a bit. Add the chicken, celery, onion and cooled sauce into a gallon-sized ziplock bag. Squeeze out all the air, and place in to the freezer. Freeze for up to 1 month. When ready to cook, thaw freezer bag out in the fridge, this usually takes about 36 hours. Cook as directed above.