Potato Leek Soup

2 pounds potatoes, peeled and cubed
3 large leeks, chopped (mostly whites, some green)
32 oz chicken broth
1 tbsp light margarine
1 tbsp salt free seasoning mix (or use spices you like)

Melt margarine in saucepan. Add leeks and saute till soft. Add potatoes, broth and seasoning. Bring to a boil, reduce heat and simmer till potatoes are soft, about 30 minutes. Ladel soup into blender and puree until smooth. Add milk or more broth if soup needs thinning.