You can buy Xanthan Gum in most health food stores (I got mine at whole foods). I used it for the first time over the holidays to make gravy and it rocked. It is a tad expensive-- $10 for the envelope. But don't let that fool you. You only need a couple of tablespoons to make a HUGE pot of gravy. It thickens up quick and what you buy will last a LONG time! Way better than making gravy with flour. Xanthan does not clump.