After pan frying the seitan and veg ,I took off the heat and poured into the sauce and let the seitan soak up the flavours. Then once I'd dealt with the other components of the meal, I added that back to the pan to warm up and thicken.
It was a bit salty, but not overly so. I used light soy sauce and fresh ginger and garlic; and made sure to balance it out a bit with sugar before the final testing.
It was okay, but I've had nicer sauces of this name
