To prepare dressing, combine first 6 ingredients, stirring with a whisk.
To prepare salad, place potatoes in a saucepan, and cover with water. Bring to a boil. Reduce heat, and simmer 10 minutes or until tender. Remove potatoes from pan with a slotted spoon. Add peas and broccoli florets to pan. Cook 1 minute; drain.
Cut potatoes into 1/4-inch-thick slices. Combine potatoes, peas, broccoli, bell peppers, and green onions in a large bowl. Add dressing; toss well.