Almost too obvious to blog about, but not quite, because it really is that good.
Six leeks: wash thoroughly, remove all the bits you wouldn’t want to eat.
Two medium sweet potatoes.
Three medium white potatoes.
Two vegie stock cubes.
Herbs: I used rosemary and sage.
Chop the leeks, scrub and prepare the potatoes for their awful doom. Put the leeks in the slow cooker. Cut the potatoes up into small pieces. Add the herbs (about a half teaspoon of each) and crumble in the stock cubes. Cover theubgredients with water, put on high for half an hour and then low for eight to twelve hours, liquidise with a stick blender, and enjoy.
(Obviously one could make this without a slow cooker, in which case I would probably cook the sweet potatoes, leeks, and white potatoes in butter or olive oil, with the herbs, until the sweet potatoes were beginning to be tender, before I added the vegie stock.)
I think of leek-and-potato soup as one of the basic soups – it’s fine, you make it a lot when leeks are in season, eat it with maybe some cheesy bread or with sour cream stirred in. But the addition of sweet potato makes the soup richer, gives the flavour more depth: it turns a good soup into a great one.
The colour of the soup becomes a murky green rather than a clean green-and-white or plain green, but who cares when it’s tasty?