In a small bowl, whisk together marinade ingredients. Arrange mushroom caps in a single layer in a non- reactive shallow pan. Pour marinade over mushrooms, cover and marinate for 1 hour, turning mushrooms several times.
Using a blender, blend vinaigrette ingredients until smooth. Taste for seasoning.
Heat a clean griddle or skillet and wipe down with an oiled cloth. Remove mushrooms from marinade, place in skillet and use a weight to press down on them. Sear them about 1 minute on each side, or until tender. Transfer mushrooms to a cutting board, slice thin and drizzle with red pepper vinaigrette.
c.1996, M.S. Milliken & S. Feniger, all rights reserved