Cook the potatoes in boiling salted water about 20 to 25 minutes, or until just tender. Drain and, when cool enough to handle, cut potatoes in half if large. Place them in a salad bowl. Sprinkle with 2 tablespoons of vinegar and 4 tablespoons of oil, toss lightly and set aside. Combine the remaining vinegar, oil, sour cream and mayonnaise in a bowl, add the Dijon mustard and garlic, and whisk until smooth. Season the dressing with salt and pepper and set aside. Add the green pepper, scallions, gherkins, pimentos and dressing to the potatoes. Toss gently and refrigerate for 2 to 4 hours before serving. To serve, return to room temperature and adjust the seasoning to taste. Serves 6. From `Art of Seasonal Cooking by Perla Meyers. Posted to MC-Recipe Digest V1 #644 by Nancy Berry on Jun 11, 1997