In a mixing bowl, combine all the dry batter ingredients and mix. Add the water bit by bit, stirring, until you have a thickish batter a bit thicker than pancake batter. Whisk and set aside 30 minutes.
Meanwhile, in a saucepan add all the ingredients for the sauce and heat through. Bring to a simmer then turn down to keep warm while cooking the chicken.
Heat the oil in a wok. Toss the chicken chunks with the cornflour and shake off excess. Whisk the batter again and add the chicken to the batter.
When the oil is ready (test with a drop of batter), add 1/2 the chicken pieces, stirring so they don't stick together. Make sure the oil is not too hot so they don't burn before the chicken is cooked. When cooked, remove the chicken pieces with a slotted spoon and place on a non-stick oven tray.
Repeat with remaining chicken. Serve with the sauce on the side.