In a small bowl, combine nutritional yeast, garlic powder, coriander, cumin, and black pepper. Dip seitan in tamari then in the yeast and spice mixture. Set aside.
Heat oil in a frying pan over medium heat. Fry seitan in batches until browned on all sides.
Seitan is a wheat gluten meat substitute. It is high in protein and has the look and feel of meat. It can be found at the supermarket or health food stores or more easily at Asian shops. If you can not locate it, you can use Fry's Protran, which is a similar product.
Nutritional yeast is a product that can be found in the bulk section at your supermarket. It may be called "savoury yeast flakes".