Another method: roast the potatoes until very soft and caramelized & then scoop out the flesh.
2 1/2 pounds sweet potatoes (about 3 medium) 4 cups apple cider 1/4 cup minced peeled fresh ginger 2 tablespoons (1/4 stick) butter or soy margarine
Place potatoes in large pot; add enough water to cover by 2 inches. Bring to boil over high heat. Reduce heat to medium-low; simmer until potatoes are very tender, about 40 minutes. Drain; cool. Peel; cut into large chunks. Transfer to processor.
Bring cider to boil in heavy medium saucepan over high heat. Reduce heat to medium-low; simmer until cider is reduced to 1 cup, about 30 minutes. Transfer cider, ginger, and butter to processor with potatoes; process until very smooth. Season with salt and pepper. (Can be made 4 hours ahead. Transfer puree to heavy medium saucepan. Cover; chill. Stir over medium heat to rewarm before serving.)
