Perfect Potato Patties and Sweet & Sour Chicken - Tips from owner of a Chinese restaurant

To make the perfect potato patty:
Mash cooked potato with sweet potato. Baste in batter made with potato flour. Cook, eg fry.
The same batter made with potato flour can be used for sweet and sour chicken. 

My friend was told this by her in-laws who run a Chinese restaurant in the USA. I asked her the secret of her delicious potato patties.