Drain the mozzarella. Pour the artichokes and tuna separately into a sieve and drain. Wash, clean and slice the tomatoes. Peel and halve the onion and cut into thin slices. Dice mozzarella.
Roughly pluck the tuna. Halve artichoke hearts. Wash basil, shake dry and pluck leaves from the stalks. Mix vinegar, salt and pepper, fold in 4 tablespoons of oil. Season again with salt, pepper and sugar. Mix the tuna, onion, artichokes, tomatoes, basil, mozzarella and vinaigrette, leave to stand for about 15 minutes. Cut the bread open. Sprinkle each half with 2-3 tablespoons of oil. Spread the topping on the bread halves.
Season again with salt, pepper and sugar. Mix the tuna, onion, artichokes, tomatoes, basil, mozzarella and vinaigrette, leave to stand for about 15 minutes. Cut the bread open. Sprinkle each half with 2-3 tablespoons of oil. Spread the topping on the bread halves. Arrange on boards, halve halves again
Waiting time approx. 15 minutes