In a large saucepan, combine potatoes, enough water to cover, and, if desired, the 1/4 teaspoon salt.
Bring to boiling; reduce heat.
Cover and simmer for 8 to 10 minutes or until potatoes are almost tender. Add corn; cook for 1 to 2 minutes more or until potatoes are tender.
Drain well; set aside.
Meanwhile, for dressing, in a large skillet cook bacon over medium heat until crisp. Remove bacon, reserving drippings in skillet.
Drain bacon on paper towels.; set aside.
Add onion to the drippings in skillet.
Cook over medium heat until onion is tender. Carefully add vinegar, broth, the 1/2 teaspoon salt, and the crushed red pepper. Bring to boiling; reduce heat.
Simmer, uncovered, for 5 minutes.
Stir in parsley and gently stir in potatoes and bacon.
Cook, stirring gently, for 1 to 2 minutes more or until heated through.
Prepare as directed. Transfer to a microwave-safe 2-quart casserole; cover and chill for up to 24 hours. To serve, microwave, covered, on 100% power (high) for 6 to 8 minutes or until heated through, stirring once. Stir before serving.