Preheat oven to 400℉.
In a large mixing bowl, add 6 cups of halved mushrooms, 1 cup oil, 1 tablespoon thyme, 1 tablespoon tarragon, and ¼ teaspoon cayenne. Toss.
Pour into casserole dish and place in the oven. Roast for approximately 20 to 25 minutes or until mushroom water has evaporated.
Remove from oven and allow mushrooms to cool to the touch. Stir in ½ cup vinegar.
Pack into a lidded container and keep in the fridge until ready to use.
Creator's Note: At The Sipp, we serve this with crostini, aioli, and shaved sharp cheese. They are also great on top of your next steak or tossed into a salad.