I have yet to make this, but here is what Beyond the Great Wall: Recipes and Travels in the Other China has to say about it: "There is something soothing and sustaning about tsam-thuk, as this classic soup is called in Lhasa dialect...a beeth broth thickened with tsampa...there's a seductive taste, almost nutty, from the roasted grain, and a smoothness on the tongue from the blend of tsampa and the butter aded at the last moment."