Beef brisket is slow cooked in a savory beer and mushroom sauce to make this sandwich. Serve it with your favorite barbecue sauce.
Trim fat from brisket. Place the meat in a large resealable plastic bag set in a large dish. In a small bowl, combine chili sauce, liquid smoke, Worcestershire sauce, steak seasoning and garlic salt. Spread the seasoning mixture on the meat, coating all sides evenly. Seal bag. Marinate brisket in the refrigerator for 8 to 24 hours.
In a small bowl, cover the dried mushrooms with hot water, if using. Let stand 20 minutes. Drain and rinse; drain again. Squeeze out excess moisture. Slice the mushrooms crosswise. Transfer the brisket and marinade to a roasting pan. Top brisket with mushrooms, if you like, and onions. Pour beer over mushrooms and onions.
Cover with foil and bake brisket in a 325 degree F. oven for 4 to 4-1/2 hours or until very tender. Uncover; pour barbecue sauce over meat. Bake, uncovered, for 30 to 40 minutes or until sauce is heated through and meat is extremely tender, adding a little water if needed.
To serve, remove meat to a cutting board, reserving sauce mixture. Use two forks to gently separate the meat into long, thin strands. Return meat to pan with sauce mixture; stir to moisten. Spoon brisket onto bread or toasted buns. Spoon additional sauce mixture over meat, if you like. Makes 10 to 12 sandwiches.