When it comes to food, Nepal is particularly known for momos, which are steamed or fried (kothey) dumplings, typically filled with minced meat. It is a cheap and delicious snack, that you will find everywhere in Kathmandu. You usually get a generous serving of 10 pieces, so when I was in the city, I had momos for lunch and for dinner most of the days.
The majority of the population in Nepal are Hindus, and they regard the cow as a holy animal that you are not allowed to kill. It is a different case for buffalos, and the momo filling is thus often minced buffalo meat. Momos are served with a tomato-based chutney (dipping sauce) that can be very spicy, but of that kind that you cannot stop yourself from eating.
I had the best momos at Yangling Restaurant, which was also one of the nicest restaurants I tried in Kathmandu. They had many different kinds of momos on the menu but also several soups and snacks, and none of the dishes was more than a dollar or two.
It was really cold when I was visiting Kathmandu, and I quickly found out that a cup of Butter Tea was one of the best ways to keep me warm. Butter tea is rather salty, and it might take a cup or two before you get used to the unusual flavor, but together with momos, it tastes really good.
Yangling Restaurant, Kaldhara Marg, Kathmandu