Kohlrabi-Mushroom Soup

3 tablespoons oil
2 medium leeks, cleaned and chopped
1 clove garlic, minced
½ lb. mushrooms, sliced
2 medium tomatoes, chopped
4 cups chicken stock
2-3 cups kohlrabi, peeled and sliced
Salt, pepper, and dill or other herb minced

Heat oil in skillet on medium-high and sauté leek, garlic, and mushrooms, stirring, about 5 minutes.  Stir in tomato and cook another 5 minutes, stirring.  Add stock, bring to boil, and add kohlrabi.  Lower heat and simmer for 15-20 minutes or until tender.  Season with salt, pepper, and fresh herb.