1. Scrub potatoes; place in a single layer in a microwave-safe casserole dish (do not pierce potatoes with a fork). Cover bowl with plastic wrap (do not allow plastic wrap to touch food); vent. Microwave at HIGH 6 minutes or until tender. Let stand 30 minutes or until cool to the touch.
2. Peel potatoes, and cut into 1-inch cubes. Place in a medium bowl. Sprinkle with onions and remaining ingredients; toss gently.