Peel and cut the potatoes, then boil them in salted water until tender. Drain and dry them a bit back in their original saucepan. Mash the potatoes well with the butter until you have a smooth but firm consistency.
Cover the kipper fillets with boiling water to soften up, then flake the fish, all the while looking out for any last little bones.
Fold the fish into the warm mash together with a handful of chopped dill, and a generous seasoning of salt and especially black pepper. Leave to cool a little, then shape into rough patties. Flatten them slightly, and then leave them to cool and firm.
Dust each fishcake lightly with flour then fry in shallow hot oil for five minutes or so on each side. Drain on kitchen paper, keeping them warm in between batches. Once all are ready, season again and squeeze a liberal amount of lemon juice over each.
The sauce is simply made by mixing the mayonnaise, garlic and parsley together and serving this on the side of the fishcakes.