From crazy plates

1 Tablespoon Butter	1 Cup Carrots, Chopped
2 Cups Leeks White Parts + 1 Inch	3/4 Tsp Dried Thyme
-Green Parts, Sliced	1/2 Tsp Salt
1 Cup Celery, Chopped	1/4 Tsp Black Pepper
4 Cups Chicken Or Veg Broth	1 Cup Buttermilk Or Milk
-(low-Fat), Or Cubes With Water	1 Tablespoon Fresh Dill, Minced
3 Cups Potatoes, Peeled And Diced

Melt butter in a large soup pot over medium heat. Add leeks and celery. Cook and stir for 5 minutes, until vegetables begin to soften.
Add broth, potatoes, carrots, thyme, salt, and pepper. Bring to a boil. Reduce heat to medium-low, cover, and simmer for 20 minutes.
Working in batches, transfer soup to a blender or food processor and puree until smooth. Return to pot. Stir in buttermilk and dill. Serve hot.