Drain the tuna while collecting some oil for later. Peel the hard-boiled eggs and cut them into large pieces. Wash, clean and dice the bell pepper and tomatoes. Peel and halve the onions and cut into half rings. Cut the sheep cheese into cubes. Remove the first leaves from the lettuce, cut into bite-sized pieces and wash.
Put the tuna, eggs, bell peppers, tomatoes, sheep cheese, onions and iceberg lettuce together in a bowl and stir. Season to taste with salt, pepper, chives and the collected tuna oil. Arrange on plates and place 4 olives on each.