Season the sardines with salt and pepper. Cut the potatoes into quarters and soak in water to remove excess starch. Cut the cheese slices into quarters and shape them into small balls.

Place the potatoes in a microwave-safe container, cover loosely with plastic wrap, and microwave at 600W for about 6 minutes until soft. Mash thoroughly and mix with salt, pepper, and mayonnaise.

Heat 1 tsp of salad oil in a frying pan over medium heat. Add the sardines and cook while breaking them apart until fully cooked. Mix the sardines into the mashed potatoes.

Divide the mixture into 8 portions. Place a piece of cheese in the center of each portion and shape into balls.

Coat each ball in flour, then beaten egg, and finally breadcrumbs.