Bengali Mustard Fish

Anjum labels this as a classic and "absolutely terrific." I could not agree more; although I never heard of this before it is something I could see making again and again.

The ingredients include:
450 g of halibut steaks - whole or quartered
3/4 tsp of tumeric
salt to taste
1 1/2 small tomatoes
3 "fat" garlic cloves
4-5 green chillies (preferably Indian finger)
1 1/2 tbsp powdered brown mustard seeds (Lisa and I debated this over dinner and it seems like one might be able to use country mustard?)
4 tbsp mustard or vegetable oil
1 1/4 tsp nigella seeds
a handful of corriander leaves (fresh)

The fish is marinated in the tumeric, while the sauce is made. The tomatoes, garlic, and 2-3 chillies should be blended. The oil is added to a pan, nigella seeds added, sizzled for 10 seconds, and then the tomato-chilli-mustard paste is added. The sauce is cooked over a moderate flame so that the excess moisture is cooked off. Reduce the heat to darken the sauce. Add 400 ml of water and add the rest of the chillies, bring to a boil and simmer for 7-8 minutes. Look for the right consistency, i.e. not too soupy. The fish should be fried in a separate pan and then added to the mustard sauce - bringing that back to a boil for a couple of minutes (this will allow the fish to really absorb the sauce). The corriander leaves are added at the end.

We've made a lot of fish dishes and this one is quite near the top of the list.