1Melt butter in a stock pot over medium heat. Add the leeks and onion and saute slowly until golden, about 12 to 15 minutes. Stir in the potatoes, stock, and lemon juice. Boil gently for 45 minutes. Let cool slightly.
2Process the soup in batches in a blender till its a slightly coarse puree.
3Return the puree to the stock pot and stir in themilk and cream season with pepper heat till simmering turn off wait 7 minutes and serve