Serves 4
For the Filling:
1 white onion
Sunflower oil
450g chicken breasts/pieces
225g thick cut roast ham or roast smoked gammon
3 teaspoons Dijon mustard
300ml sour cream
1 teaspoon fresh tarragon
For the Pastry:
450g plain flour
2 teaspoons baking powder
½ teaspoon salt
125g butter
1 egg yolk
100-150ml cold water
1 egg
Extra flour