Shomal (meaning North in Farsi) is a great Iranian restaurant specializing in North Iranian cuisine.
It is a little pricey but the food you get is amazing and you will savour every last bit of it. With large portions and distinctive tastes, I take all of my friends to Shomal when I want them to try out Iranian food.
Definitely try the Mirzaghasemi (a garlic eggplant type appetizer) as well as one of the Kebabs. The Koobideh and Joojeh kebabs are absolutely amazing and I`m sure you will love it.
Also don`t forget to try out the authentic in house made doogh (which is pretty much a minty yogurt based drink - can be carbonated or not).
The atmosphere and music is very authentic and beautiful made to represent the northern regions of Iran.