- Mix together the sauce ingredients.
- Place the potatoes in a pan of boiling water and simmer for 10 minutes. Drain and return to the pan.
- Add the butter and peas and mash.
- Add the tuna, chives, egg yolk, season with salt and pepper and mix well.
- Turn the mixture out onto a board and divide into 8. Form them into cakes. Put the beaten eggs in a bowl and the breadcrumbs in another bowl. Dip the fish cakes in the egg and then into the breadcrumbs.
- Heat about 2 tablespoons of olive oil in a large frying pan and then add the fish cakes. Cook on a medium heat until browned on both sides.
- Serve with salad and the sauce.