Whisk water, ketchup, rice vinegar, sugar, water and starch in a small container and set aide.
In a large mix bowl, combine ground beef, onion, garlic, ginger, water, starch, dark soy sauce, sesame oil and salt, insert a pair of chopsticks into the mixture, stir in one direction for a couple of minutes until the meat became sticky.
Spoon some meat mixture into your hand, roll between your hands to shape into a 1.5- inch meatballs, repeat the process until all the mixture is used.
Heat oil in a skillet over medium heat, add in the meatballs, pan fry until both sides are browned, remove from pan and set aside.
Pour the sauce mixture into a sauce pan, bring to a simmer over low heat and add in the meat balls, simmer for 20 minutes or until cook through with lid on, stir occasionally.