How to Make It
Steam the potatoes in a basket over simmering water until tender, about 25 minutes. Transfer to a plate and let cool completely. Peel the potatoes, then slice them 1/4 inch thick.
Meanwhile, add the green beans to the steamer and cook for 3 minutes. Scatter the zucchini over the green beans and steam until both are just tender, about 3 minutes. Spread the beans and zucchini out on a baking sheet and let cool completely.
In a small bowl, mix the olive oil with the basil, parsley, vinegar, garlic, dill, oregano and thyme; season with salt and pepper. In a medium bowl, toss the potatoes with all but 2 tablespoons of the vinaigrette, then transfer to a platter. Add the beans, zucchini and remaining vinaigrette to the bowl and toss to coat. Mound the beans and zucchini on the potatoes and serve.