Pound the pork with a meat cleaver, then slice into 4x1cm strips. Marinate with rice wine, 1/3 teaspoon salt and MSG. Let sit for 30 minutes.
Make the batter by beating together the eggs and 3 tablespoons cornflour. Set aside.
Make the sauce by mixing together the chicken stock, sugar, vinegar, soy sauce, remaining salt and remaining cornflour.
Heat the oil in a wok to 140 degrees C. Drop the pork into the batter and stir to coat. Add the pork, one piece at a time to the hot oil. Deep fry until lightly golden. Remove with a slotted spoon.
Heat the oil to 170 degrees C and return the pork to the hot oil. Fry until golden brown, remove with a slotted spoon and place onto a serving dish. Drain all, but 2 tablespoons oil in the wok.
Heat the oil in the wok until hot. Stir-fry the ginger and garlic until aromatic. Add the spring onions and sauce mixture; stir until the sauce begins to thicken. Pour the sauce over the pork and serve.