A simple cure is a mixture of sugar and salt which is rubbed into fish in order to draw out moisture and preserve it by killing any bacteria present. Cured trout is readily available in the supermarkets, but it is much cheaper to do it at home and lasts for a long time in the fridge. It’s also an impressive dish to serve to guests, considering the small amount of work it takes.
Coarse salt is most often used for curing as it is less refined, and the large crystals help to draw out more moisture. The sugar will not give the trout a sweet flavour, but helps to bulk out the salt so that the fish is not too strongly flavoured.