In a bowl combine ground pork, water chestnuts, mushrooms, egg, cornstarch, onion, salt and pepper.
Mix very well and form into balls, about 1 to 1 & 1/2 inch in diameter. Set aside.
In a deep saucepan, heat about 1 Tbsp. cooking oil and saute garlic, onion and tomatoes until soft.
Add water and allow to boil for a minute then drop pork balls in the boiling liquid and simmer for about 10 to 15 minutes until the meatballs are cooked.
Season with salt and pepper then add the misua and stir cook for a few minutes until misua is soft and cooked.
Serve hot and garnish with spring onion.