How to Make It
Preheat the oven to 300°. In a medium enameled cast-iron casserole, bring the water to a boil with the tarragon and thyme sprigs and 1 teaspoon of salt.
Add the pearl onions, cover and simmer over low heat until tender, about 8 minutes. Using a slotted spoon, transfer the onions to a large shallow baking dish. Add the carrots to the simmering water, cover and cook until tender, about 8 minutes. Transfer to the shallow dish. Repeat with the haricots verts (about 4 minutes) followed by the zucchini (about 3 minutes), and, finally, the red and yellow peppers (about 3 minutes). Cover the vegetables with foil and keep warm in the oven.
Boil the vegetable cooking liquid over high heat until reduced to 1 cup, about 5 minutes. Remove from the heat and whisk in the butter, 1 tablespoon at a time. Stir in the minced tarragon, parsley, chives and garlic. Season with salt and pepper. Pour the sauce over the vegetables, toss gently and serve.
If you don't have time to prepare all of the vegetables called for in this recipe, select at least three, making sure to use a variety of colors.