Roasted Sweet Potato Soup with Lemon Yoghurt
I roast and eat sweet potatoes like nobody's business.  I buy at least 3 Ibs. each week, and before I know it, it's time to hit the stores again.  To keep things interesting, I've been roasting them with a little walnut oil and a dusting of cinnamon, and all of a sudden, the Hungryman has