I make these with perch (persico), which is cheap. But cod would be good too.
I mix everything in the Magimix: 400 gm fish (no bones!), chopped parsley, 50 gm pecorino, 50 gm breadcrumbs, 100 ml yogurt. pepper and a little salt. I take spoonfuls of the mixture and make flat patties. These I rest in the fridge for half an hour and then shallow fry a few minutes each side.
A quick sauce to go with them would be: yogurt, anchovy paste, fresh basil and olive oil.
I must admit that though these are good, proper fish cakes made with potato are better!