1In 2-quart saucepan, heat potatoes, hot water, onion and salt to boiling; reduce heat. Cover and simmer 5 minutes; drain. Rinse with cold water until potatoes are cool; drain thoroughly.
2In large bowl, stir together mayonnaise and mustard. Add potatoes and remaining ingredients; toss until coated. Cover and refrigerate at least 1 hour until chilled.