Wipe the mushrooms clean with a damp cloth and cut into quarters.
Place in a large bowl and add the chopped parsley.
In a small bowl or glass jar, combine the mustard, vinegar, lemon zest, lemon juice and sweet chilli sauce.
Whisk in the olive oil slowly until an emulsion starts to form.
Taste the vinaigrette and season to taste with salt and pepper. You can also add more sweetness if you need to.
Add the vinaigrette to the mushrooms and toss.
Cover the salad with plastic wrap and leave to marinate in the fridge for 10 to 15 minutes before serving.