These meaty mushrooms are marinated in Syrah, a medium-bodied red wine, for two hours before grilling. They can be served with a fruity white or full-bodied red wine.
1. Poke holes all over mushrooms, making sure not to break them. Place in large glass baking dish.
2. Combine wine, shallots, garlic, peppercorns, and thyme in small saucepan, and season with salt. Bring to a boil. Reduce heat to medium-low, and simmer 5 minutes. Pour wine mixture over mushroom caps, and stir to coat. Cover, and marinate 2 hours.
3. Preheat grill or broiler. Remove mushrooms from marinade, and discard liquid. Grill mushrooms 5 minutes on each side, or until browned and juicy. Serve on buns with burger fixings.