Cook the chicken breast with the water, ginger, garlic, pepper, vinegar and soy sauce till it is cooked through, reserving about ¼ cup of the liquid.
Shred the cooked chicken and set aside.
Saute the onion in the butter just till it becomes translucent.
Add the green chillies and saute for anoher 30 seconds.
Add the flour to the above mixture and whisk quickly to make a smooth paste.
Add the reserved ¼ cup of water and stir til you have a thick sauce.
Add the red pepper flakes and shredded chicken and mix well.
Cool the mixture till it is at room temperature.
Preheat the oven to 400° farenheit
line 2 baking sheets with parchment paper
Remove your pastry from the fridge and cut each sheet into a square
add a tablespoon of the filling in the center of each square.
fold the square into a triangle and seal the edges with the tines of a fork to prevent them from opening during the baking process.
Beat the egg yolk and brush on top of each patty.
bake for 15-20 minutes till the pastry rises and browns on top.