How to Make It
Place onion and vinegar in a small bowl; toss to coat.
Place potatoes in a medium saucepan; cover with water to 2 inches above potatoes. Bring to a boil. Reduce heat; simmer 15 minutes or until tender. Remove potatoes from pan with a slotted spoon; cool slightly. Thinly slice potatoes. Bring water in pan to a boil. Add green beans; cook 3 minutes or until crisp-tender. Drain. Rinse beans under cold water; drain.
Cook bacon in a small skillet over medium heat 6 minutes or until crisp. Remove from heat. Drain vinegar from onions into skillet with bacon and drippings. Add oil, mustard, salt, and pepper, stirring with a whisk. Arrange lettuce wedges on 4 plates; top evenly with onion, potatoes, green beans, and radishes. Drizzle with vinaigrette, and sprinkle with chives.