Boil the potatoes in salted water for about 20 minutes until al dente. Meanwhile, drain the corn and tuna. Slice the tuna with a fork.
Cut the onions and peppers into small pieces. Rinse the potatoes, peel and cut into pieces. Finely chop the parsley and place in a large bowl with all the prepared ingredients and the olives. Boil the eggs in the water for about 8 minutes. Then quench, peel and halve. Arrange the salad with the eggs just before serving.
Put the ingredients for the salad dressing in a tall container and emulsify with a hand blender. Even if it looks like a lot of sauce at first glance, pour everything over the salad, mix and then let it steep for at least 30 minutes. Mix again before serving and season with salt, pepper and sugar if necessary. Now decorate with the egg halves.