1.Preheat oven to 250°C. Brush chicken with 2 tbs mayonnaise. Place, skin-side up, on a wire rack set over a baking paper-lined baking tray. Roast for 15 minutes or until golden. Reduce oven to 150°C and cook for a further 30 minutes or until cooked through. Remove and rest for 10 minutes.
2.Combine lemon juice and remaining mayonnaise in a bowl. Season. Place apple, celery leaves and stalks, onion, nuts and raisins in a large bowl. Toss with dressing.
3.To make tarragon oil, combine tarragon, vinegar and extra virgin olive oil in a bowl.
4.Serve chicken with Waldorf salad and a drizzle of tarragon oil.