1 Mix the cream, mustard, curry, salt, pepper, vinegar and tomato purée in a bowl, until
you achieve a smooth-looking sauce.
2 Cut the fish into suitable pieces and transfer them to an ovenproof tin.
3 Slice the onions and lay the slices on
top of the fish pieces.
4 Pour the sauce over the fish and onions.
Place the tin in the oven and bake at the bottom of the oven at 200 degrees C (392 degrees F) for 30 minutes. Then reduce the temperature to 100 degrees C (212 degrees F) and continue to bake for a further 20 minutes. Remove the tin from the oven and let the fish stand for 10 minutes before serving.