Wash and drain the mushrooms.

Bring a medium sized pot of boiling water (about half way full of water) to a boil; add vinegar, 2 dashes of salt and the mushrooms. Boil for 8 minutes. Drain; transfer mushrooms to a large bowl and cool mushrooms to room temperature before adding the dressing.

While mushrooms are cooling dice peeled and pitted avocados. Chop the green onions and set aside.

When mushrooms have cooled add the dressing, avocados, and green onions. Toss everything together to combine and refrigerate for at least an hour for flavors to meld together.