3 pounds small red potatoes
1 tablespoon olive oil
1 1/2 cup fresh corn (cut from about 3 ears) or thawed frozen
1/2 cup buttermilk
2 tablespoons mayonnaise
1 tbs white-wine vinegar
3 large scallions, chopped
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, scallions, and salt and pepper to taste, tossing to coat.