Step 1

Boil, steam or microwave potato until just tender; drain. Cover; refrigerate 30 minutes.

Step 2

In a large bowl, combine potato with onion, tomato and olives.

Step 3

In a small bowl, whisk sour cream, vinegar and milk. Pour half of the dressing over salad and toss gently to combine. Add basil, tossing gently to combine. Drizzle with remaining dressing.