Who doesn't enjoy a Weird Al reference? There are a few things you can do to substitute the ground beef. Tonight we ground the leftover seitan in the blender. You can also use veggie crumbles, or fry up crumbled tofu that has been frozen and thawed. In a rush, you could use that Old El Paso taco seasoning (I think it is vegan), but I like to use a mix of chili powder, cumin, cinnamon, cayenne, and oregano.