Into a food processor add the bay leaves, peppercorns, mustard seeds, garlic, chile, onion, parsley, and thyme and pulse-chop into a paste. Place the vinegar, 1/4 cup water, sugar and salt in a pot and bring to a simmer to dissolve. Then add the paste and simmer for 1 to 2 minutes. Place the mushrooms in a container and douse with the hot brine; cover and steep 1 minute. Stir and drizzle with extra-virgin olive oil.
Recipe courtesy of Rachael Ray