Serves 8. Can be doubled.
Preheat oven to 400°F. Spray baking sheet with vegetable oil spray. Arrange potatoes, skin side down, on sheet. Spray potatoes with vegetable oil spray. Sprinkle with sugar and thyme. Season with salt and pepper. Toss to coat. Arrange potatoes, cut side down, on same baking sheet. Roast potatoes until tender, turning potatoes over halfway through roasting, about 35 minutes.
Whisk lemon juice and olive oil in small bowl to blend. Season dressing to taste with salt and pepper.
Combine lettuce, green onions and tarragon in large bowl. Add hot potatoes and dressing. Toss to coat. Serve warm.