Directions:

• In a small saucepan, cover the potatoes with cold water. Partially cover pan and cook over moderately high heat until the potatoes are tender, 25 to 30 minutes. Drain thoroughly and set aside to cool slightly.
• Preheat the broiler. In a small saucepan, combine the vermouth, shallots, sugar and ¼ teaspoon salt and bring to a boil. Carefully ignite the hot vermouth with a long kitchen match and boil until the flames die down and the vermouth is reduced by half, about 4 minutes. Stir in the vinegar and mustard.
• Cut the warm potatoes into 1/2" wedges. In a medium bowl, toss them gently with the vermouth mixture.
• Separate the onion into rings and spread on a lightly oiled baking sheet. Brush with the olive oil and season with salt. Broil as close to the heat as possible or 3 to 5 minutes, or until the slices are soft and beginning to char.
• Toss the onion with the walnut oil and tarragon. Add to the potatoes. Toss to coat and sprinkle with pepper.