Cook the fish in a frying pan until white and flaky, then shred
Meanwhile, prepare the dipping sauce by combining all the ingredients then cover and refrigerate
Spread 1/2 cup of the breadcrumbs on a plate
In a large saute pan, over medium heat, add a thin layer of olive oil
Meanwhile, in a medium mixing bowl, combine the shredded fish, eggs, onion, sour cream, lemon juice, mustard, salt, cayenne pepper, and the other 1/2 cup of the breadcrumbs
To make the fish cakes, grab a golf ball-sized handful of the fish mixture and squeeze it together
Slightly flatten the fish cake and coat the outside with the breadcrumbs on the plate and place on an empty plate
Repeat with the rest of the fish mixture
When the oil is hot, cook the fish cakes until brown, about 3-5 minutes per side