1Using a fork or a small whisk, mix together the vinegar and lemon juice with the garlic, salt, pepper and Dijon mustard. Whisk in the olive oil and yogurt.
2Steam the potatoes above 1 inch simmering water for 10 to 15 minutes, until tender. Transfer to a large salad bowl and season with salt and pepper. Add the tuna and toss with 1/4 cup of the dressing while the potatoes are hot.
3Bring a pot of water to a boil, and fill a bowl with ice water. When the water comes to a boil, add a generous amount of salt and add the green beans. Cook 4 to 5 minutes, until just tender. Transfer to the ice water, then drain. Dry on paper towels. Add to the salad bowl, along with the red or green pepper, cucumber, hard-boiled eggs, lettuce and herbs. Garnish with the tomatoes, anchovies and olives, and serve.