Bring water and salt to a boil in a medium to large pot and place cleaned mushrooms into pot. Cover, bring to boil and simmer on low boil for five minutes. Drain and cool mushrooms.
Place the remaining ingredients, except the olive oil, in a medium bowl and whisk to combine. Slowly drizzle in the olive oil whisking while you pour.
Add the cooled mushrooms and place in a sealed container or zip lock bag and refrigerate at least overnight or longer. Serve slightly chilled or at room temperature.