Whisk the red-wine vinegar, Dijon mustard, garlic, salt, pepper, and thyme together. Slowly whisk in the extra-virgin olive oil until the dressing is emulsified, then taste and adjust the vinegar or salt as needed.

Place the potatoes in a saucepan and cover them with cold salted water. Bring to a boil and simmer for 10–15 minutes, depending on their size, until fork-tender; drain, cool slightly, halve or quarter, and toss while warm with 1–2 tablespoons of vinaigrette.

Place the eggs in a saucepan, cover with cold water, and bring to a boil. Remove from the heat, cover, and let stand for 10–12 minutes, or simmer gently for about 9–10 minutes; cool in ice water, peel, and halve.

Boil the trimmed green beans in salted water for 3–4 minutes, until bright green and just tender. Transfer them immediately to ice water, drain and pat dry, then toss with a little vinaigrette.

Arrange the lettuce on a large platter, then add the potatoes, beans, tomatoes, eggs, tuna, olives, anchovies, red onion, and herbs in separate sections or a composed pattern. Spoon the remaining vinaigrette over the salad just before serving.

Let the assembled salad sit for 5–10 minutes so the vegetables absorb some of the dressing without becoming soggy. Serve at room temperature or lightly chilled, seasoning with additional salt and pepper if necessary.