Bring a medium pan of water to the boil and fill a large bowl with ice-cold water.
Drop the green beans into the pan. After 2, then drain and tip the vegetables into the icy water – this will cool them quickly, helping to keep their bite and vibrant colour. After 1-2 mins, drain and set aside in the colander while you prepare the other ingredients.
Dry your bowl, pour in the dressing ingredients with plenty of seasoning and whisk together.
Add the chicken, radishes, spinach, watercress, cooled and drained vegetables, and the lettuce, and gently toss everything together until well coated in the dressing – the easiest way is to use your hands. Pile the salad onto a large platter, serve straight away.