Olive oil
2 1/2 pounds of sweet potatoes (or butternut squash), peeled and cubed
2 large or 4 small apples (or Russet or Yukon Gold potatoes), cubed (peel potatoes if using)
1/2 teaspoon cayenne, or to taste (optional)
6 cups chicken broth
1 teaspoon apple cider or balsamic vinegar (or to taste), optional
Salt and pepper to taste
Preheat oven to 450 F. Lightly oil two sheet pans or baking sheets. Add the cubed sweet potato and drizzle on another tablespoon or so of olive oil. Using your hands, make sure all of the sweet potatoes are coated lightly with the oil. Season with salt and pepper. Place pans in oven and roast sweet potatoes for about 15 minutes, or until edges are getting brown and larger cubes are tender when pierced with the end of a sharp knife. Remove from oven and set aside to cool before proceeding.
If using a blender or food processor, add 1/4 of the apple, 1/4 of the sweet potatoes, 1 1/2 cups of broth, 1/4 of the cayenne and 1/4 of the vinegar to the container and process according to manufacturer's instructions. Pour into a 4 quart saucepan or Dutch oven, and add another batch of the ingredients to the container and process. Repeat for remaining ingredients.
If using an immersion blender, place ingredients in a 4 quart saucepan or Dutch oven and using immersion blender, puree ingredients until desired consistency.
Place saucepan over medium heat and heat, stirring occasionally, until heated through.