1. Cook the eggs for 10 minutes in boiling water. Once cooked, remove them and pass them under cold water. Book. Pour a little water into a pan and bring it to a boil. Arrange the green beans in the casserole dish, cover and let heat for about 10 minutes.
2. Meanwhile, strain the tuna and crumble it. Wash the salad and wring it out. Wash the tomatoes and cut them into quarters. Take the hard-boiled eggs and shell them. Cut them into quarters. In a salad bowl, mix salad, green beans, tomatoes and boiled eggs. Drop some black olives.
3. Prepare the lightened vinaigrette. In a ramekin, mix the salt and the vinegar. Add the mustard, water and oil, whisking with a fork and then pepper to your liking. For a creamier sauce, you can add 1 to 2 tbsp. white cheese 0% MG. Pour the seasoning over the salad and serve.