Cook potatoes in a Dutch oven in boiling water to cover 30 minutes or until tender; drain and cool. Peel and cube potatoes.
Whisk together lemon juice and next 5 ingredients in a large bowl; whisk in oil in a slow, steady stream. Add potato; gently toss to coat. Spoon into center of individual serving plates; sprinkle evenly with bacon and half of grated cheese.
Arrange salad greens around potato salad, and top with onion slices and remaining cheese. Serve immediately.