Step 1Place lentils, mushrooms, onions, bell peppers and water to cover in 4-quart saucepan. Bring to boil over medium-high heat then reduce heat and simmer until tender, about 1 hour. Drain lentil mixture and cool slightly, 10 minutes.
Step 2Place lentil mixture in mixing bowl and add bread crumbs, basil, oregano, thyme, chili powder, pepper to taste, tamari, beaten egg whites, salt, Mozzarella, walnuts and water. Mix well. Pour into lightly greased 9-inch-square baking pan, spreading evenly; it will fill the pan.
Step 3Bake at 350 degrees until lightly browned, about 30 minutes. Cool 15 minutes before cutting and serving with a favorite gravy, if desired.