Peel and cut the potatoes into 2cm cubes. Soak in water, drain, and microwave in a covered container for 6 minutes at 600W. Mash while hot and let cool. Mince the onion.

Heat 1/2 tbsp of salad oil in a frying pan. Sauté the ground meat and minced onion over medium heat until the meat changes color. Season with salt and pepper, then let cool.

In a bowl, mix the mashed potatoes, sautéed meat mixture, miso, and mayonnaise. Shape into 6 equal portions and form into balls. Chill well. Coat each ball in flour, beaten egg, and breadcrumbs in sequence.

Heat oil in a pot to 170°C (about 3cm deep). Fry the croquettes, turning occasionally, until golden brown and crispy.