MALAY FISH PICKLE

The origin of the pickle is not very clear to me, here is a recipe that appears in the book "Foods of the World", on African cuisine in which Lauren Van der Post says Malay fishermen were the ones who invented the technique.
Ingredients for about 6 people
170 ml vegetable oil
1 Kg albacore fillets, cut in loins and then cut in half
100 g sugar
1 teaspoon urfa chile
2 tablespoons Madras curry
1 tablespoon finely chopped fresh ginger
4 bay leaves, 2 crumbled and 2 whole leaves
1 teaspoon coriander
Salt
500 ml apple vinegar
250 ml water
Clean and dry the fish and pass it through some flour, fry the fish in 125ml of vegetable oil, until golden brown. Set aside.
Clean the frying pan and prepare the marinade, put in a frying pan 60 ml of vegetable oil and when it has been heated a little, fry the onion until golden, carefully not to burn it and for round 8 minutes, then add the sugar, urfa chile, curry powder, the ginger root, bay leaves, coriander and salt and stir over the heat for about 2 minutes, stirring constantly, mix vinegar and water and pour in a fine stream, bring to boil and then lower the heat and let it boil gently for about 10 minutes.
Remove the skin and bones of the fish and then alternate in a jar or glass container with the marinade. Leave to rest for about two days in the refrigerator and then you can serve with part of the marinated onion and its sauce, if possible in one of the amazing dishes of Marta Morales :)