Get a small spicy chicken with potstickers. They have it every day and it is delicious. If you're extra hungry go for the regular sized, but normally the small is enough.
The mongolian beef on Tuesdays is why you hear whispers of "mongo tuesday" in all offices near the Tower Deli. When you hear the call "One Mongol", you'll know you're in the right place.
Everyone seems to love the spicy chicken; it's the daily special on Monday and Thursday. I personally prefer one of Wednesday's specials: chicken (green) curry on rice. Tasty!