In a large saucepan (or similar sized pot) bring 4 cups of water to a rolling boil, then dissolve 1 Tablespoon + 1 teaspoon kosher salt in the water and then add mushrooms.
Let mushrooms cook for about 4 minutes, stirring occasionally. Their volume will decrease by about a third.
Drain mushrooms and leave to cool while you prepare the marinade.
In a mixing bowl, add all marinade ingredients (starting at the lower end of the measurements) except olive oil and parsley and stir or whisk until all salt and sugar are dissolved.
Taste the mixture and adjust seasoning if desired.
Add olive oil and parsley and stir or whisk to combine.
Pack mushrooms in an airtight jar or container (I used a 16 oz. mason jar) and add marinade. Then use a spoon to press down and distribute the marinade ingredients more evenly.
Refrigerate at least 8 hours and up to 5 days. Serve at room temperature. Enjoy!
