Cook potatoes in boiling water 10 min. or until tender. Meanwhile, cook and stir bacon in skillet on medium heat until crisp. Remove from skillet with slotted spoon; drain on paper towels. Discard drippings in skillet. Add onions, peppers, celery and dressing to skillet; cook on medium-high heat 3 to 4 min. or until vegetables are crisp-tender, stirring frequently.