Cut potatoes into 2cm cubes and the aubergine into 1cm cubes.
Heat 1 tbsp oil in a frying pan and fry the mustard seeds for 1 minute until they start popping. Add the chilli. Stir in the potatoes and aubergine and fry for 1 minute.
Stir in the turmeric and 200ml water. Cover and cook for 8 minutes. Stir in the coconut milk, season well and bring to the boil, cook uncovered for 7-8 minutes until tender.
Serve garnished with chopped coriander.