Whisk together fish sauce, oil, and sugar until the sugar is completely dissolved. Stir in shallot and garlic, and season with pepper. Add pork and pound the meat into the marinade until evenly coated. Marinate, refrigerated, for 1 hour.
Place pork between the palms of your hands and squeeze out excess liquid. Put drained meat in a container and place in freezer for 1 hour. Put partially frozen pork in a food processor and pulse to loosen the meat, about 2 minutes. Add potato starch and continue pulsing until mixture has firm paste-like consistency, about 5 minutes. Form into meatballs.
Slide 3 to 5 meatballs onto each skewer. Grill over a barbecue or on a well oiled grill pan over medium high heat until the meatballs are cooked through, rolling them around in the pan, about 6 minutes.