Peel the potatoes and cut into 2 cm pieces. Pour 700 ml of water into the bowl and place the potatoes in the steam basket and then in the appliance.
Launch the steam program for 30 mins. Rinse and drain the potatoes. Empty water from the bowl and attach the kneading/grinding tool tool. Thinly slice the onions.
Place the potatoes, onions, parsley, peas, tuna, egg, salt and pepper in the bowl. Mix on speed 6 for 15 s. Transfer mixture to a separate bowl.
Using wet hands shape mixture into 16 small 5 cm patties. Toss and coat in the breadcrumbs, cover with plastic wrap and place in the fridge for 30 mins before cooking.
Heat a little of the oil in a large frying pan and cook patties in batches for 1-2 mins each