If you've ever made the mistake of mashing potatoes in a food processor, you'll know that the blades give them the consistency of Uhu. As do the blades of a liquidiser when you blend the potatoes in a soup. The solution is to cook the potatoes separately, and mash them. Serves 4.
3 medium potatoes
1 garlic clove, unpeeled
3 medium leeks
Peel the potatoes, and cut them into chunks as you would for mash. (I usually cut mine into pieces about 2cm square.) Cook them in about 200ml of chicken stock, with a little salt. If you put a lid on the pan, the potatoes do not have to be submerged in liquid - and it is better to go easy on the stock now than to end up with a thin soup.
Cut off the roots and the tough leaves of the leeks. Split them down the middle, then slice them vertically, and wash them. Allow them to soak for a few minutes, so that the grit can disperse. Drain them, and put them into a saucepan with about 25ml stock, a knob of butter, and a little salt. Cook them gently in a covered pan until soft and glossy (about 10 to 15 minutes), adding a little more stock if they threaten to catch.
When the potatoes are soft, fish out the garlic, slip it from its skin, return it to the pan, and mash it with the potato.
Add enough stock to the leeks to enable you to blend them. Put them in a liquidiser, or use a stick blender.
Combine the leeks and the potato, adding more stock if necessary. Warm up the soup gently - if you boil it, you'll bring out the glueyness in the potatoes. Check the seasoning. Away from the heat, stir in another knob of butter.