I use bacon fat any time I want to sautee anything.
btw, soy sauce isn't all that bad, imo. It's a fermented form of soy, and most of the nasties are killed off in the fermentation process. Soy sauce does usually have gluten, but I use San-J organic gluten-free soy sauce. Not perfect, but a small price to pay for giving stir fries a great flavor.