1. Cut ribs into single rib pieces and chop into 7.5 cm (3 in) lengths.
2. Place ribs in a large saucepan, cover with cold water and bring to the boil, then simmer for 15 minutes.
3. Drain. Put hot spice mix, turmeric, ginger, onion, vinegar and tomato puree in a food processor.
4. Add 75 ml (2 1/2 fl oz/1/3 cup) water and process until smooth.
5. Place ribs in a non-metal dish, pour over spice mixture and stir to coat well.
6. Cover loosely and leave in a cool place for 2-3 hours.
7. Transfer ribs to a grill pan. Heat grill.
8. Cook ribs for about 15 minutes, turning occasionally and basting with any remaining marinade, until well browned and very tender.
9. Serve hot, garnished with spring onions and tomatoes.

Serves 4.