Bring 400 ml water and 1 level teaspoon of salt to the boil. Add the rice, cover and let it swell at low heat for about 20 minutes until the rice has absorbed all the liquid. Let the rice cool down. In the meantime drain the tuna. Peel onions and cut into fine rings.
Clean, wash and drain spring onions and peppers. Cut the spring onions into diagonal very thin rings. Quarter peppers and cut or slice them into fine strips. Wash parsley, dab dry and chop except for something to garnish. Mix vinegar, parsley, salt and chilli. Finally, add the oil. Mix rice, spring onions, bell peppers, tuna, vinaigrette and 3/4 of the red onions. Let the salad stand for about 1 hour and season with salt and chili. Arrange on a plate and sprinkle with remaining onion rings.
Mix vinegar, parsley, salt and chilli. Finally, add the oil. Mix rice, spring onions, bell peppers, tuna, vinaigrette and 3/4 of the red onions. Let the salad stand for about 1 hour and season with salt and chili. Arrange on a plate and sprinkle with remaining onion rings. Serve garnished with parsley