In a large soup pot, melt butter and sauté leeks over medium heat for 5 minutes until clear. Add pepper and sauté about 10 minutes.Add chicken broth and simmer for 30 minutes.Using a hand blender, puree until smooth. (Or using a blender, puree in batches.) Add buttermilk and stir well. Chill.
Keep in a pretty pitcher in the fridge and enjoy with crusty breads and your favourite cheeses. When its chilly out, warm this soup — it’s great both ways. 1 large pepper yields 1 cup chopped pepper and 1 large leek yields 1 cup chopped leeks.