Add a little extra something to your classic prawn cocktail with this grown up spicy dressing.
To make the dressing, put all the ingredients except the chilli flakes into a bowl and mix to combine. Cut the prawns into smaller pieces and fold them through the dressing.
Place a small amount of watercress in each serving glass or bowl. Add an even amount of the prawn mixture. Sprinkle with chilli flakes and serve.