Put oven rack in middle position and preheat oven to 500°F.

Pour milk over bread crumbs in a large bowl and stir until liquid is absorbed. Add ground meat, egg, water chestnuts, salt, chopped cilantro, 1 tablespoon soy sauce and 2 teaspoons oil and mix with your hands until combined well. Shape 3 tablespoons meat mixture into a ball and transfer to a 13- by 9-inch glass baking dish. Make more meatballs with remaining mixture, arranging meatballs about ½ inch apart in baking dish. Bake until cooked through, about 15 minutes.

Meanwhile, stir together lime juice, water, sugar, remaining 4 tablespoons soy sauce and remaining 2 teaspoons oil in a bowl until sugar is dissolved.