To make Honey-Mustard Vinaigrette, in small bowl, whisk together lemon juice, honey, vinegar and mustard until well blended. While whisking, slowly drizzle in oil until completely incorporated. Season
with salt and pepper.
In medium saucepan, cook potatoes in 2 inches simmering water, covered, 20 to 25 minutes or until tender. Drain and cool.
In large bowl, mix potatoes, Honey-Mustard Vinaigrette and green and red onions. Just before serving, mix in tomatoes and parsley.