First of all, what is datsi? It's the Bhutanese cheese, a soft, melted cheese which the locals use to make local delicacies (and bound to disagree with your digestion, too). Ema means chilli. Kewa is potato, and shamu is mushroom. Did you, then, guess what these foods mean? Ema Datsi is the national dish, a plate of chillies served mixed with datsi. Not only is it the national dish, it is also one of the spiciest dishes. I've tried it only twice or thrice, and got out with a fiery tongue. I'm not saying it's bad! But is it ever spicy! Kewa datsi is pretty much the same thing, but, as you might guess, instead of chillies, it is served with potatoes. The datsi in this dish is quite hot, because otherwise the taste would have been bland. The shamu datsi is my favourite, because it's full of mushrooms, and I personally adore mushrooms, especially the sangay-shamu and button mushrooms sometimes found in the local market in Thimphu. These are big, tough mushrooms, which, in good cooking, can be simply heavenly. Anyway, back to the subject. The datsi in the shamu datsi is also quite spicy, but not as much as the ema datsi, of course.
All the Bhutanese love these dishes, and mostly eat them every day... with... rice, rice, and more rice!