Method

Put the chopped onion into iced water and soak for 5 minutes, then drain well.

Cut the fish into 1½ - 2cm cubes and rub with the ½ tsp salt. Leave for a minute. Add the citrus juices and the chilli and leave to marinate for 10 minutes. Check the seasoning and adjust if necessary.

Divide the fish and marinade between 2 bowls, scatter with coriander, and serve immediately.