Prepare barbecue (medium-high heat) or use a hot grill pan brushed with olive oil.
Lay mushroom strips in a large shallow bowl. In a small bowl whisk together the liquid smoke, maple syrup and salt and pour over mushrooms. Marinate mushrooms at room temperature for 15-20 minutes making sure they are covered with the marinade.
Remove from marinade and grill slowly for about 5 minutes on each side or until they are soft and juicy with grill marks.
Season with salt and pepper.
Divide the mushrooms, lettuce, tomato slices and bean spouts evenly to make 4 sandwiches.
Spread your favorite condiment on top. I like to puree some roasted red peppers from a jar with a little salt and pepper and lemon juice to spread on top.