Place the soup bag in large pot of water. Bring to a boil and lower to a simmer until heated all the way through.
While the soup is heating up, peel and cut the potato into a medium dice and blanch in salted water for 5-8 minutes. Just until slightly softened. Reserve and keep hot.
Thinly slice the serrano pepper, pick the celery leaves, and fine julienne the tomato and set aside.
To plate ladle 8 ounces of the soup in a bowl and place 1/2 cup of the blanched sweet potatoes in, top with garnishes.