In a mixing bowl, combine all-purpose flour with hot and cold water until a shaggy dough forms. Knead for about 10 minutes until smooth and elastic. Cover with a damp cloth and let it rest for 30 minutes.

While the dough is resting, prepare the filling by mixing ground beef or pork, chopped green onions, minced ginger, and soy sauce in a bowl until well combined.

Divide the dough into equal pieces and roll each into thin rounds, about 4 to 5 inches in diameter. Spoon a small amount of filling into each round's center, fold over to create a half-moon shape, and seal the edges tightly.

Heat vegetable or peanut oil in a skillet over medium heat until shimmering. Fry the sealed pies for 3-4 minutes on each side until golden brown and crispy.

Transfer the cooked pies to a paper towel-lined plate to absorb excess oil. Serve warm with black vinegar or soy sauce for dipping.