Place green beans in a large pot of boiling water, and cook 3 to 4 minutes or until crisp-tender. Immediately plunge into ice water to stop the cooking process. Cover and chill up to 2 days.
Combine mushrooms, 1 Tbsp. vinegar, and next 4 ingredients on a large rimmed baking sheet coated with cooking spray. Spread mushrooms in a single layer.
Roast at 425° for 20 to 25 minutes or until tender and browned, stirring once or twice. Reheat green beans in the microwave at HIGH 3 minutes or until hot. Combine green beans, roasted mushrooms, and remaining 1 Tbsp. vinegar; toss well.