Yes, you can enjoy a delicious meatball sub even if you're following a vegan diet. These vegan meatballs are made with a combination of lentils, mushrooms, breadcrumbs, ground flaxseed, minced garlic, chopped parsley, dried oregano, salt, and pepper. Cook the lentils until tender and then pulse them in a food processor with the mushrooms until finely chopped. Transfer the mixture to a bowl and add the remaining ingredients. Shape the mixture into meatballs and bake them in the oven until golden brown. To assemble the sub, slice a vegan baguette lengthwise and spread some marinara sauce on both sides. Place the vegan meatballs on one side of the baguette and top with vegan cheese and sautéed onions and peppers. Toast the sub in the oven until the cheese is melted and bubbly. Serve hot and enjoy the plant-based deliciousness of this vegan meatball sub!