In a medium pot, bring the water and vinegar to a boil. Boil the mushrooms for 3 minutes, then drain and set aside while you make the marinade.
In a large bowl, whisk together the remaining ingredients to make the marinade. Add the mushrooms, and stir to combine. Taste, and add a few more pinches of salt if you'd like.
These can be served right away or kept in the fridge for several days.