Hard-boil the eggs, allow to cool, remove the shells and cut each into four lengthways. Wash and dry the lettuce, break the leaves into small pieces no bigger than about 1½" (4cm) square. Cut each tomato into about six equal sections and cut out and discard the loose, wet seeds, leaving just firm flesh, then cut each section into two or three pieces. Drain the mozzarella cheese and chop roughly into small pieces. Drain the tuna and, using a fork, break it into small bite-size pieces. Drain the sweet corn. Peel and finely chop the shallot.
Prepare the Summer Oil Dressing in a large salad bowl. Retain two tablespoons of it in a cup then add all the ingredients (prepared as above) except for the eggs into the salad bowl and gently 'toss' the salad in the oil until it is all thoroughly coated. Lay the egg pieces on top and pour the reserved dressing over them. Serve with crusty whole wheat bread.