Put the eggs in a saucepan of cold water. Bring to the boil, then reduce the heat and simmer for 10 minutes. Stir during the first few minutes to centre the yolks. Cool under cold water, then peel and cut into quarters. Meanwhile, score a cross in the base of each tomato, and put in a bowl of boiling water for 10 seconds. Plunge into cold water and peel away from the cross. Cut each tomato into eight sections.
Cook the beans in a saucepan of boiling water for 2 minutes, rinse under cold water, then drain.
For the dressing, put the oil and vinegar in a screwtop glass jar, seal tightly and shake to combine.
Rub the garlic over the bottom and sides of a platter. Arrange the lettuce over the bottom. Layer the egg, tomato, beans, red pepper, cucumber and celery over the lettuce. Scatter the onion and tuna over them, then the olives, anchovies, capers and basil. Drizzle the salad with the dressing, and serve.