Preparation Combine all ingredients except water and butter in a deep 12-inch heavy skillet or wide 3- to 6-quart heavy pot and toss to coat with oil. Add water to skillet and bring to a boil. Cover skillet tightly and simmer vigorously over moderate heat, shaking skillet occasionally, until vegetables are tender, about 10 minutes. Transfer vegetables with a slotted spoon to a platter, discarding thyme sprigs, then boil cooking liquid 1 minute to emulsify oil. Remove from heat and add butter, swirling skillet until butter is incorporated. Pour sauce over vegetables. Cooks' note:All ingredients except butter can be combined in skillet 1 hour ahead and kept, covered, at room temperature (make sure cut sides of potatoes are submerged in water).
Preparation Combine all ingredients except water and butter in a deep 12-inch heavy skillet or wide 3- to 6-quart heavy pot and toss to coat with oil. Add water to skillet and bring to a boil. Cover skillet tightly and simmer vigorously over moderate heat, shaking skillet occasionally, until vegetables are tender, about 10 minutes. Transfer vegetables with a slotted spoon to a platter, discarding thyme sprigs, then boil cooking liquid 1 minute to emulsify oil. Remove from heat and add butter, swirling skillet until butter is incorporated. Pour sauce over vegetables. Cooks' note:All ingredients except butter can be combined in skillet 1 hour ahead and kept, covered, at room temperature (make sure cut sides of potatoes are submerged in water).