Make sauce: In a bowl, stir together all ingredients until sugar dissolves. Set aside.
Make meatballs: In a large bowl, combine egg white, onions, cilantro, ginger, pepper, salt, and cabbage. Stir in panko. Add shrimp and pork, breaking up with your fingers, and mix well with your hands. Chill until mixture is firm enough to shape, about 15 minutes. With wet hands, roll meat mixture into 1 1/2-in. balls.
Heat oil in a heavy 12-in. frying pan (preferably nonstick) over medium-high heat. Cook meatballs until well browned all over, turning as needed, 8 to 10 minutes total. With a slotted spoon, transfer meatballs to paper towels, then to a platter.
Serve with lettuce leaves, dipping sauce, and daikon and carrot.
Mastering meatballs. They sound rustic, but they're delicate things that suffer from over-handling. Here are tips for making them come out right.
Mixing: Always start by mixing the bread crumbs (which keep the meatballs from getting tough), any liquids, and seasonings—then add the meat. Stop when the mixture looks evenly blended; don't overwork it.
Forming: Dampen your hands with cold water to keep the meat mixture from sticking while you roll it into balls. If it's still sticky, let it sit for a few minutes in the fridge.
Browning: A good crust helps meatballs retain their shape—important if they're going to simmer in a thick sauce. If you plan to eat them on their own or add them to broth, though, a light pan-frying will do the trick.
Note: Nutritional analysis is per serving.