Aubergine curry with tomatoes, ginger and fennel seeds

600g aubergines, ideally Asian finger aubergines

150ml vegetable oil

40g fresh root ginger, roughly chopped

40g garlic, roughly chopped

2 green cayenne chillies, finely chopped

2 tsp fennel seeds

1 tsp cumin seeds

1 tbsp coriander seeds, freshly ground

½ tsp turmeric powder

400g chopped tomatoes, fresh or from a can

½ tsp freshly ground black pepper

1 tbsp coriander, freshly chopped

1 tsp mint, freshly chopped