Rinse potatoes and chop, set aside. I didn't peel my potatoes. Chop leeks and soak them in a deep bowl of water to clean them. Scoop them out with your hands (they float) or with a skimmer.

Put 4 cups of leeks and 4 cups of potatoes in a large pot. Add 6-7 cups of water to the pot, boil for 30-40 mins until the potatoes are tender.

Take the pot off of the stove, add a stick of butter and with an immersion blender, blender, potato ricer or a fork, blend/mash the leeks and potatoes. Don't liquefy them, you want little bits for texture.

(The picture isn't mine, I just found it online to illustrate how to use/what is an immersion blender) :D

Let the soup cool for a few minuets, it's best served chilled.