Sweet potato pasties

8 oz shortcrust pastry (= 1:2 margarine:flour)
1 onion
2 small/medium size sweet potatoes
4 oz frozen peas
½ tsp ginger
½ tsp chilli
¼ tsp turmeric
½ tsp ground cumin
1 tsp coriander
¼ tsp mustard powder
salt and pepper

Preheat oven to Gas Mark 6 / 200 °C. Cut up the sweet potatoes into chunks and boil for around 15 minutes until fairly soft. Dice them.
While they are cooking, make the pastry and leave to stand.
Chop and fry the onion and add ½ tsp ginger; ½ tsp chilli; ¼ tsp turmeric; ½ tsp ground cumin; 1 tsp coriander; ¼ tsp mustard powder, salt and pepper. Add the spices and season to taste with salt and pepper. Cook gently for 4-5 minutes. Allow to cool.
Roll the pastry into 4 circles. Place filling into centre of pastry and fold into a pasty. Brush with soya milk and make a small vent in each one. Bake for 20-30 minutes.