Cook beans in boiling water 5 minutes or until crisp-tender.
Drain and plunge beans into ice water; drain.
Place potatoes in a saucepan; cover with water. Bring to a boil. Reduce heat, and simmer 5 minutes or until tender; drain. Return potatoes to pan over medium heat.
Add 2 tablespoons vinegar to pan; bring to a boil.
Remove from heat.
Combine remaining 2 tablespoons vinegar, oil, 1/4 teaspoon salt, and pepper in a small bowl, stirring with a whisk.
Drizzle beans with vinegar mixture; toss well to coat.
Place beans on a serving platter; arrange potatoes over beans.
Sprinkle with remaining 1/4 teaspoon salt, parsley, and bacon.