Add potatoes to a medium saucepan, cover with cold water, and season with salt. Bring to a simmer over medium-high heat and until fork-tender, about 5-6 minutes. Drain and transfer to a medium bowl. Reserve the saucepan for eggs.
Next, bring a separate saucepan of salted water to a boil. Fill a bowl with ice water. Add the haricots verts to the boiling water and cook until crisp but tender, 3-4 minutes. Drain and put into the ice water to cool. Drain and pat dry.
Place the eggs in the reserved saucepan and cover with cold water about 1 inch over the eggs. Bring to a simmer over medium-high heat, then cover. Remove from the heat and let stand for about 10 minutes. Drain and run under cold water. Peel under cold running water.
To make the dressing, combine vinegar, oil, zest, citrus juice, shallots, Herbes de Provence, mustard, ½ teaspoon salt, and ½ teaspoon pepper in a Mason jar. Cover and shake until emulsified.
Season tomatoes with a pinch of salt and pepper and toss in a bowl. Add 2 tablespoons of dressing to the potatoes and toss. Quarter the hard-cooked eggs.
