Cut your pork into large strips and place in a blender. Mix for 1 minutes. Add salt, pepper, soy sauce and egg. Then drain 1/3 of the scallion and ginger water in. Mix for another 1 to 2 minutes. Then repeat the process and add the remaining 1/3 water. Make sure all of the water is completely absorbed.
Place 2 tablespoons of cornstarch and the last 1/3 ginger and scallion water.Blend until the meat turns pink and fluffy.
Fry the 1/2 of the tomato until soft. And add enough water and 1/3 of the bean sprouts. Add smashed ginger and simmer for at least 25 minutes after boils.
Place the remaining bean sprouts in and scoop the meatballs too. When the meatballs float on the surface, continue cook for another 2 minutes. Add salt to taste and serve hot. The meatballs come out very juicy and tender with a slightly touch of sour and sweet taste. I highly commend trying at least once in cold winter days.