I made a scrumptious gravy using chicken drippings, marsala, and cornstarch, and maybe a bit of this and that for seasonings. It was rich and thick and totally perked up my leftover roast pork. Unfortunately, I packed my leftovers for lunch the next day, and when I opened up my tub the gravy had gone all watery. I can't tolerate gluten (e.g., wheat flour), so what else could I use? Or do I need to use a different technique if I utilize cornstarch? Would love any and all tips. Thanks!