An old favourite, tasty and warming in the cold weather.
Top and tail the leeks, slice longways half way through, and then open up a little to rinse under running water. Roughly chop the leeks, then wash and peel the potatoes and cut into chunks.
heat the oil in a pan and add the vegetables. stir to cover with the oil, and simmer covered with a lid for 10 minutes, stirring regularly
Add the stock, stir, and cover for another 10 mins until the potatoes are soft.
Remove from the heat and liquidise/blend to achieve the consistency you want. Season with salt and pepper to taste, and stir in a little cream if required.