You need a (large) big bowl.
First wash all the ingredients, cut the lettuce, tomatoes into small pieces and cucumber slices, all in one place (?) and use bandaja (?) olives and tuna for salad decoration.
Put the oil, vinegar and salt to your taste and ready to eat.
Photo from: http://biocuidados.files.wordpress.com/2008/10/ensalada-verde3-1.jpg