Question: can hoisin sauce be substituted for soy sauce?
Answer: Soy sauce I generally substitute half soy sauce to hoisin. For example in a recipe using 3-4 tablespoons of hoisin sauce, I'd substitute 1-2 tablespoons soy sauce. Add more if needed after tasting. If you want some sweetness you could add some extra white or brown sugar or honey but I generally don't bother.