To save time (and washing up), this soup needn't be puréed, but can be left slightly chunky - just make sure it's cooked for long enough, so that the lentils are very tender. If the soup isn't going to be pureed, ensure that both the bacon and onion are finely chopped. To freeze, leave the soup to cool, pack into freezer containers, cover, seal and freeze for up to 3 months. Allow the soup to defrost before reheating.