Cut potatoes into 3/4-inch wedges. In a large saucepan of boiling salted water cook potatoes until just tender, 8 to 10 minutes, and drain well.
In a large skillet heat oil until hot but not smoking and cook corn, covered, over moderately high heat, shaking skillet occasionally, until browned, about 3 minutes. Cool corn slightly and combine with potatoes in a large bowl. Potatoes and corn may be cooked 1 day ahead and chilled, covered.
In a small bowl stir together buttermilk, mayonnaise and vinegar. To potatoes and corn add buttermilk mixture, season with salt and pepper and toss to coat. Garnish with scallions
Recipe courtesy of Gourmet Magazine