Harissa adds smoky heat to these silky make-ahead mashed sweet potatoes.
Slideshow: Great Sweet Potatoes
Preheat the oven to 400°. Poke the sweet potatoes several times with a fork and bake on a baking sheet for about 1 hour, until tender. Let cool slightly.
Peel the sweet potatoes and transfer to a food processor. Add the butter, sour cream and harissa and puree until smooth. Season the potatoes with salt and white pepper. Serve right away.