Whisk together first 8 ingredients in a large bowl; add mushrooms.
Let stand at least 30 minutes, stirring occasionally.
Serve at room temperature with a slotted spoon.
Garnish, if desired.
For Entertaining, High-Style 'Shrooms: Dress up this marinated mushroom salad by serving it in a footed dish or trifle bowl.
Wine & Dine: We recommend the following wines with dinner: Morgan Monterey Syrah, Chateau Souverain Dry Creek Zinfandel, or Bleasdale Langhorne Creek Shiraz-Cabernet.