Finely chop the tuna fillet. Blanch the cabbage leaves in hot water (scald briefly), lift out and pat dry. Chop the onion into small cubes and place in a bowl. Mix with eggs and tuna. Salt, pepper and season with teriyaki sauce. Boil the peeled potatoes in salted water until soft and strain. Wash the arugula leaves and drain well. Now cut the cooked potatoes into quarters lengthwise and mix with a little olive oil and salt. Place in an ovenproof dish and heat in a preheated oven at 160 degrees for about 15 minutes. Meanwhile, place the blanched cabbage leaves and spread the tuna mixture on each. Roll up each cabbage leaf and fry in a pan in a little oil until golden brown. Pour on a little (about 1 tablespoon) teriyaki sauce and let the roulades steep briefly. Remove the potatoes from the oven and mix with arugula. Flavor with balsamic vinegar and serve together with the roulades.