- Portion size 6 servings
In a large saucepan, melt butter over medium heat; cook sweet potatoes, garlic, onion and ginger, stirring often, for 5 minutes. Pour in stock; bring to simmer. Cover and cook over medium heat for 20 minutes or until vegetables are very tender.
Transfer soup, in batches, to blender or food processor; pur?until smooth. Transfer to large bowl. Whisk in milk. Refrigerate for about 4 hours or until chilled. (Make ahead: Refrigerate for up to 12 hours).
Ladle into chilled bowls. Garnish with dollop of yogurt.