4 fish steaks (tilapia, carp or ilish are particularly authentic)
1 tsp ground turmeric
1 ½ tsp chilli powder
salt, to taste
a large pinch of sugar
sunflower oil, for frying
50g yellow mustard seeds
4 fresh chillies, slit lengthways (non-chilliheads should remove the seeds!)
6 tbsp mustard oil (or, if unavailable, 6 additional tbsp sunflower oil)
2 tomatoes, roughly chopped
2 tsp onion seeds
½ unripe mango, sliced
½ tsp ground cumin
a few sprigs fresh coriander, chopped