Methods 1) Heat the oil in a large saucepan. Add the leeks and onions and cook for 5 minutes, stirring regularly. Add the garlic and cook for another minute. 2) Add the potatoes and stock to the pan and bring to the boil. Reduce the heat and simmer for 20 minutes.
3) Blend until smooth, in batches if necessary. Return to the pan and reheat. Serves 4.