Place all the sauce ingredients in a blender and blend until smooth.
Place the chicken in the slow cooker, pour over the sauce, and cook on high for 3-4 hours.
Break up the chicken with two forks and stir back into the sauce.
Leave the chicken mixture to cool until you are ready for it.
Make the pastry by mixing together the flour, salt and turmeric.
Cut the butter into small cubes and rub it into the flour until you have the texture of breadcrumbs.
Add the water little by little, sitting it in with a spoon, until it comes together as dough. You might not need to use all the water.
Form the pastry into a ball, wrap it in foil or cling film, and chill in the fridge for at least half an hour.
Roll the pastry out to about 0.5 cm thick, and cut out 8-10 circles using the top of a mug or small pot.
Place a small amount of the chicken filling, with the frozen peas added, onto each circle.
Note: You will have leftover filling, which can be served separately, or you could double the pastry for a larger batch.
Brush the edges of the pastry circle with the beaten egg.
Fold the pastry over and seal the edges together and use a fork to crimp the edges.
Place the patties on a baking tray lined with baking paper.
Bake at 180 degrees for 20-25 minutes, until golden brown.