Traditional Icelandic fish soup (halibut soup) - Fiskisúpa (lúðusúpa)

This soup is among the oldest recorded Icelandic recipes. It's sweet-sour taste is unusual for fish-based soups.Traditionally, the recipe is given for halibut, but you can also use salmon, trout, wolf-fish or lumpfish, or other fatty fish.1 1/2 kg fresh fish with bones, cut into pieces to fit in the pan1 1/2 litre water2 tbs white vinegar2 tsp salt2 bay leaves50 g flour100 ml cold water1/2