1.Dust pork in cornflour, shaking off excess. Heat oil in a wok on high, until a pinch of cornflour sizzles when added.
2.Cook pork, in 2 batches, 4-5 minutes each batch, until crisp; drain on paper towel.
3.Meanwhile, in a large saucepan, add water, sugar, ginger and garlic. Stir on low heat until sugar dissolves. Bring to boil on high; simmer 4-5 minutes, without stirring, until syrupy.
4.Add pork to syrup with vinegar and soy sauce; simmer 1-2 minutes.