1. Cut any skin and fat off the pork and cut the meat into 2.5 cm (1 in) cubes. Season 2 tablespoons of the soy sauce with salt and pepper. Dip the pork first in the soy sauce, then into 2 teaspoons of the cornflour.
2. Heat the 2 tablespoons of oil in a saucepan. Stir in the vinegar, sugar, the remaining soy sauce and the pineapple juice. Cut up the pineapple and add it to the sauce.
3. Simmer for 1 minute. Dissolve the remaining cornflour in a little cold water and add it to the sauce to thicken it.
4. Heat the remaining oil to 180 c (350f) in a deep fryer. Fry a few pieces of meat at a time, for 6 minutes per batch, until brown and crisp, drain and keep hot. Stir the meat into the sauce and serve immediately.
Instead of pork fillet, you could use leg of pork or chicken equally successfully for this recipe.