Tusy Mung Bean, Tarragon & Kohlrabi Soup

Tus, on the northern plain of Iran not far from Mashhad, was a Silk Road center until it was destroyed by the Mongols in the 13th century. It is the birthplace and burial site of Ferdowsi, author of the Iranian national epic, The Shahnameh, or Book of Kings. I have named this dish in honor of his birthplace, although the recipe was actually inspired by summers spent in Mashhad, a city of pilgrimage shrines and beautiful gardens.