Spicy aubergine curry

1 teaspoon cumin seeds

4 teaspoons coriander seeds

1 teaspoon cayenne pepper

2 green chillies, deseeded and sliced

½ teaspoon ground turmeric

4 garlic cloves, crushed

2.5 cm (1 inch) piece of fresh root ginger, peeled and grated

300 ml (½ pint) warm water

400 g (13 oz) can reduced fat coconut milk

1 tablespoon tamarind paste

1 large aubergine, thinly sliced lengthways

salt and pepper

4 mini plain naan breads, to serve