Preparation:
Preheat oven to 200 degrees. Wash the sweet potatoes, dry them with a towel and place them on the foil in the oven. Bake for 20-30 minutes. The cooking time depends on the size of the vegetable, so after 20 minutes you need to check the readiness with a fork: the sweet potato should be very soft inside.
Sweet potatoes are a great source of fiber, vitamin B6 and vitamin A, potassium and manganese (http://nutritiondata.self.com/facts/-and-vegetable-products/2666/2)