Fill a small saucepan with water; add sweet potatoes. Bring water to a boil and cook sweet potatoes until tender enough to break apart with a fork, 25 to 30 minutes.
Transfer sweet potatoes to a food processor or an immersion blender cup, reserving the cooking water. Blend sweet potatoes until smooth. Add 1/2 to 3/4 cup cooking water and blend until desired consistency is reached.