Combine yogurt, capers, salt, sugar, and cayenne pepper.Mix well, and let it rest in the fridge while you finish cooking the fish cakes.
2. Mincing fish in food processor
Peel the potatoes and grate them using the coarsest side of the box grater.Grate the onion on the same side.
3. Frying
Heat half the oil over medium-low heat in a large, non-stick frying pan.Fry the codfish and potato mixture by forming small patties with two tablespoons of the patties, never more than three at a time. Once brown on the bottom side, flip carefully and cook until golden brown all over.When you've gone through half of the mixture, add the remaining oil to the pan and heat again. Continue with the process until there is no more mixture.
4. Serving
Place on a plate covered with a paper towel to absorb excess oil.Serve alongside the yogurt dressing.