When in Gangtok you have to try their momos. From pork to beef to sabji(veg) they have it all. Steamed or fried, in oil or butter, all varieties, all types. Price ranges from 30 rps to 200 rps depending on the meat and the place you eat in.
But what is more specially local which you cant get in Banglore of Delho are their tee momo which is basically a big momo with no filling, steamed and had with a gravy. Considered healthy by them, and also very filling.
Or a taypo, which is a bigger tee mom with meat/ egg filling, all steamed. Eating one is probably going to fill you up.
Another dish similar to this is Phaley- they are semi circular and filled with similar stuffing but are never steamed, always fried.
We used to eat near a small shack near Paljor stadium, where you used to get tasty items for very cheap rates. Even their aloo or meat Thukpa which is basically soupy noodles are tasty. Or their wai-wai, which are packet noodles eaten raw without having to boil them in water.