To prepare leeks, slice leeks into rings and separate. Soak in a large bowl of cold water for a few minutes and rinse. Scoop them out and drain.
Heat a large pot to medium high heat and add butter. When butter has melted, add leeks, onions, celery, garlic, and potatoes. Saute for about 5 minutes, or until the leeks are softened, stirring often to prevent sticking.
Add the broth and chili powder. Bring to a boil over high heat. Reduce heat to low and simmer covered for about 20 minutes. Stor occasionally. Potatoes should be quite soft. Remove from heat.
Using an immersion blender or blender, puree potatoes until soup is creamy. Add chives and stir through. Adjust salt and pepper to taste.
Seafood Chowder Option: add mixed seafood, and clams including liquid to the soup. Bring to boil. Remove from heat and let sit for 10 minutes before serving.
Bacon and Vegetable Garnish Option: In a medium frying pan on medium heat, add butter or oil. Add onion, celery and bacon and sautee until bacon and vegetables are browned. Remove from heat and add chives.