In a large bowl, combine the ground pork, tapioca flour and 3 tablespoons water and mix well. Then add soy sauce, sesame oil, sugar and remaining ¾ teaspoon salt and mix well. Add prepared vegetable mixture and stir to combine.
Place 1 tablespoon pork mixture in the center of a potsticker wrapper. Brush the edges of the wrapper with water and pleat to seal (see notes). Transfer to a baking sheet dusted with flour. Repeat with remaining pork mixture and potsticker wrappers.
Heat remaining 1 tablespoon vegetable oil in a large fry pan over medium-high heat. Add half of the potstickers to pan and cook for 3 minutes or until brown on the bottom. Pour ⅓ cup water over the potstickers and cover with a lid. Reduce heat to medium and cook for 5 minutes. Then remove lid and cook until water evaporates, about 1 minute. Serve with soy-vinegar sauce.
Make the soy-vinegar sauce:
In a medium bowl, combine all the sauce ingredients; let sit for at least 15 minutes before serving.