For the rice vinegar sauce, peel and finely grate the ginger. Caramelise 100 g sugar until golden yellow. Add soy sauce and SushiMix, dissolve the caramel. Add the ginger and boil down the liquid until 3⁄4 Stir 1 tablespoon starch and 3-4 tablespoons cold water until smooth.
Stir into the boiling sauce and simmer for 2-3 minutes. Let it cool down.
Wash and possibly halve the tomatoes. Peel and finely chop the onion. Clean, wash and cut Pak Choi into rough strips. Cut bread into about 8 slices. Rinse tuna cold, dab dry and cut into bite-sized pieces.
Heat 1 tablespoon of oil in a frying pan. Fry the tuna for 2-3 minutes all around (the fish pieces should still have a pink core inside, then they are juicy and tender). Season with salt and pepper.
Heat 2-3 tablespoons of oil in a frying pan one after the other. Fry the slices of bread in it in portions on each side until crispy, then let them drip off on kitchen paper. Heat 1 tablespoon of oil. Fry the onion, tomatoes and Pok Choi for 2-3 minutes while turning.
Season with salt and pepper.
Clean, wash, spin dry and chop all salads. Break bread into pieces. Mix everything with rice vinegar sauce. Sprinkle with pine nuts. Serve with Japanese mayonnaise.