Boil salted water add green beans cook about 5 minutes until tender crisp drain immediately and submerge in a bowl of ices water, (this stops the cooking process and retains the nice green colour of the beans).
Pat dry with paper towel or a tea towel.
Place in a salad bowl along with mushrooms and chives.
Place the rest of the ingredients in a jar and shake well to blend.
Pour over the mushroom and beans toss gently. Place in a covered container and refrigerate for a couple of hours.