1/4 cup red-wine vinegar
2 1/2 tablespoons minced shallot
2 teaspoons Dijon mustard
1 large garlic clove, minced and mashed to a paste with 1/2 teaspoon salt
1/4 cup extra-virgin olive oil
1/2 teaspoons minced dried thyme
1/2 tablespoons dried basil
3/4 lb green beans (preferably haricots verts), trimmed
1 1/2 lb small (1- to 2-inch) potatoes (preferably Yukon Gold)
1 1/2 lb (1-inch-thick) tuna steaks
Vegetable oil for brushing
1/4 cup drained bottled capers (1 1/2 oz) (I omitted)
1 pt cherry or grape tomatoes
2/3 cup Niçoise or other small brine-cured black olives
4 hard-boiled large eggs, quartered
3 tablespoons finely chopped fresh parsley and/or basil
Whisk together vinegar, shallot, mustard, and garlic paste in a small bowl until combined well, then add oil in a slow stream, whisking until emulsified. Whisk in thyme, basil, and salt and pepper to taste.
Cook beans in a 4- to 6-quart pot of salted boiling water, uncovered, until crisp-tender, 3 to 4 minutes, then immediately transfer with a slotted spoon to a bowl of ice and cold water to stop cooking. Add potatoes to boiling water and simmer, uncovered, until tender, 15 to 20 minutes, then drain in a colander. Halve potatoes while still warm (peel if desired) and toss with 2 tablespoons dressing in a bowl, then cool.
Brush tuna with oil and season with salt and pepper, then grill on lightly oiled rack(I pan fried), uncovered, turning over once, until browned on outside but still pink in center, 6 to 8 minutes total. Let tuna stand 3 minutes, then break into large (3-inch) pieces. Transfer tuna to a large platter and drizzle with 2 to 3 tablespoons dressing and top with capers.
Transfer potatoes to platter with tuna, reserving bowl. Drain beans and pat dry. Toss beans in bowl with 1 tablespoon dressing and salt and pepper to taste, then transfer to platter. Toss lettuce in bowl with 2 tablespoons dressing and salt and pepper to taste, then transfer to platter. Toss tomatoes in bowl with 1 tablespoon dressing and salt and pepper to taste, then transfer to platter.
Arrange olives and eggs on platter and sprinkle salad with parsley and/or basil. Serve salad with remaining dressing on the side.
I made the beans and potatoes earlier in the day, they held just fine. I did toss potatoes with dressing while still warm.