1. Trim stems from spinach and cook leaves in boiling water for 2-3 minutes, until tender.
2. Drain thoroughly and rinse under cold running water.
3. Put in a food processor and process to smooth puree. set aside.
4. Pre-heat oven to 160C (325F/Gas 3).
5. Cut pork into 2.5 cm (1 in) cubes.
6. Heat oil in a large frying pan and fry pork until browned all over.
7. Transfer to a casserole using a slotted spoon.
8. Add onions to pan and cook, stirring, for 10-15 minutes, until a rich brown.
9. Add garlic, ginger, garam masala, turmeric, bayleaf, tomatoes and chillies.
10. Cook, stirring, for 2-3 minutes, until tomatoes have softened.
11. Add yogurt and 155 ml (5 fl oz/2/3 cup) water and stir.
12. Pour water and cook for 1 1/4-1 1/2 hours, until pork is cooked through.
13. Remove bay leaf, stir in spinach and salt, re-cover and cook for a further 10 minutes.
14. Garnish and serve.

Serves 4.