Mustard-Mashed Borlotti Pie

For 4 (or 3 hungry people):

200g tin of borlotti beans, drained and rinsed
200g tin of chopped tomatoes
4 mushrooms, chopped
1 green pepper, chopped
1 small carrot, chopped
Large handful of spinach
Small red onion, chopped
1 piece of stem ginger, grated

1 large sweet potato, chopped
2 tsp wholegrain mustard
1) Gently boil the sweet potato for about 20 minutes.
2) Meanwhile, fry the onion and ginger in a deep saucepan.
3) Add the beans, mushrooms, pepper and carrot. Stir well for 5 minutes.
4) Pour in the chopped tomatoes, mix around and leave to simmer over a low heat for 10 minutes.
5) In the last few minutes, stir in the spinach. Pour into a pie dish.
6) Drain the potatoes and add the mustard. Mash well and spoon over the pie filling. Stick under the grill for 5 minutes.