Divide the water dough into 10 equal portions.
Roll out the dough into a flat square.
Spread 1 tablespoon of oil paste in the centre of the dough (be careful not to get to close to the edge).
Fold over dough in half and press down to seal the seams.
Gently press down the dough and flatten.
With a rolling pin, roll the dough out into a slender rectangle.
Coil the dough up (like making a jelly roll) and turn it 90 degrees. Flatten and repeat.
Roll out the dough again, coil it up and turn it 90 degrees another 2 more times. (This produces the flaky layers).
Once the dough is rolled out to a long rectangle, add 1.5 teaspoon of (about 18g) of char siu filling to the centre.
Fold up the dough to cover the filling and seal/crimp the edges with a fork.
Place the pastry onto a parchment-lined baking sheet.
Repeat with the remainder.