Sweet Potato Soup Base

I got the idea from Lidia Bastianich to make soup bases that pack a lot of flavor on the weekend, then freeze them and thaw them as needed, adding various ingredients on the fly to take them in different directions. I like to concentrate the base, which saves freezer space, and then thin it out when I make a finished soup. Before you thin it out (and jazz it up) for the final soup, this base may remind you of a certain fluffy Thanksgiving side dish (minus the mini-marshmallows, thankfully), but there are some key differences. Besides the lack of cream or sugar, the most important one is the cooking method: Rather than boiling peeled cubes of sweet potato, I like to roast them, concentrating the complex flavor, which is highlighted by subtle hints of thyme and curry. This makes an especially vibrant backdrop to such treatments as Sweet Potato Soup with Chorizo, Chickpeas, and Kale (page 43). There are many other possibilities. You can sprinkle ground chipotle or pimenton (smoked Spanish paprika) for heat and/or smoke, or add toasted pecans, yogurt (or sour cream or crème fraîche), and other sausages or cured meats.