Peel the potatoes in advance and keep them submerged under cold water to prevent discoloration.
Smash the garlic clusters on their sides to seperate the cloves. Cut off the large end of the cloves and crush the clove by laying the cloves on a flat surface, and pressing down on them under the side of the blade of a wide, bladed knife. Remove the peelings from the crushed cloves.
Inspect the leeks and remove any parts of the plants that are withered or discolored. Chop the onions. Coarsely chop the leeks, including the leaves. Saute the leeks, onions, and garlic in peanut oil. Peanut oil seems to work best but olive oil or corn oil may be used. Saute until tender. Set aside in a strainer to drain any excess oil.
Select a pot large enough to cook the potatoes with some room to spare for the soup. Add 3 cups of chicken stock and 3 cups of water. Make sure the chicken stock is clear; containing no fat. If homemade chicken stock is not available then substitute with instant chicken broth, but use locally prepared stock if possible.
Cook the potatoes in the stock/water combination for 25 - 30 minutes, or until done. Remove the potatoes and reduce heat under the pot, but keep the liquid hot.
Drain the potatoes and insure the sauted vegatables are drained. Place potatoes and the drained vegatables in a food processor and blend on medium to high speed until smooth. Return the blended mixture to the liquid in the soup pot. Stir well and increase heat.
Heat just to boiling. If the soup appears to be too thick at this stage slowly add a little more stock or water. If desired add salt and pepper to taste. The soup is ready to serve at this point, especially as low fat or a lite soup. But you can add milk or cream. When the liquid reaches boiling point, add the milk or cream. Stir. milk produces a thinner soup than the cream. Cream or Half-N-Half provides a full flavor with more body. Heat to just below the boiling point. Be careful at this stage and do not boil after adding the milk or cream. Too much heat at this time will cause the soup to stick to the pot and loose flavor.
Serve immediately with fresh baked bread or homemade croutons.
Additional comments: The amounts of the ingredients are not critical to a successful soup. If you like garlic its hard to put too much in this receipe. The amount of onions can be varied also. The more onions, the better it seems to be. A ratio of one bunch of leeks to one pound of potatoes is OK. But more leeks doesn't spoil it either.
For people without a large food processor: The potatoes can me prepared as if making mashed potatoes (with a mixer) but with just potatoes. If the mixture becomes too dry add water or milk while beating. Blend the sauted vegetables in the food processor and add to the beaten potatoes. Blend until smooth before adding to the stock.