Soop naw mai is a Northeastern ("E-san") traditional dish known in the west as Bamboo Shoot Yum. Soop naw mai is less popular than som tum (green papaya salad) among people in Bangkok, but tastes great. I personally like it better than som tum.
One thing that you should know is that when you add the fish sauce, the dish may develop a strong smell. Don't worry. The smell does not reflect the taste at all.