Preheat the oven to 200 degrees. Place the mushrooms in stainless baking pan, 9 x 13-inches. Pour the vegetable oil over the mushrooms. Tie the remaining ingredients together in cheesecloth, forming a small pouch. Tie the pouch with butcher's twine. Place the bouquet garni in the oil and cover with foil. Place in the oven and cook for 2 hours. Drain the mushrooms reserving the oil.
Yield: 1 pound