Clean, wash and cut the beans into bite-sized pieces. Put them into boiling salted water and cook for about 15 minutes. Then rinse with cold water and drain. Hard boil the eggs in about 10 minutes. Then rinse with cold water, peel and cut into slices. Wash and clean the tomatoes, possibly cut into slices. Clean and wash romaine lettuce and cut into strips.
Peel onion, slice into fine rings. Drain the tuna and pluck it into large pieces with a fork. Arrange prepared ingredients and olives in portions. Season vinegar with salt, pepper and sugar. Fold in the oil. Drizzle vinaigrette over the salad. Serve garnished with lemon and basil