Onions peel and in wafer-thin rings plan or cut. Mix 200 ml cold water and 1 tsp salt. Let the onions steep for about 30 minutes, so that they become soft and lose some of their pungency.
Rinse fish fillet, dab dry. Place on the work surface with the flat side down. Spread your fingers over the fillet side to find any remaining bones. Pull out with tweezers.
Cut the fillet into approx. 1 cm large even cubes. Squeeze limes and measure approx. 1⁄8 l juice. Mix with 1 tsp. salt and add to the fish. Marinate for about 15 minutes (see box on the left).
Clean the chilli, cut lengthwise, remove seeds, wash and chop. Wash the coriander, shake dry and chop coarsely. Drain the onions. Mix everything with the fish.
The lime dressing with chilli and coriander, in which the fish is marinated and served, is called "tiger milk". South Americans usually add more brew to the fish to strain a part of the tiger milk than to drink shot. With a shot of pisco (brandy made from grapes) the tiger milk becomes panther milk.