7 cups unbleached bread flour
3 cups whole wheat bread flour
4 1/2 cups water
1 1/2 tsp sea salt
8 cups vegetable stock or water
1/4 cup tamari
1 piece of kombu
1 piece of wakame

Put the flours in a bowl. Mix the water and salt together and add to the flour. Stir until the mixture forms a ball, then knead for 10 minutes with the dough hook of a food processor. Cover with water and let stand 1 hour.

Pour off the water and rinse the dough under running water until the water is almost clear. Divide the dough into 2 balls.

Put the stock into a large soup pot and bring to the boil. Add the tamari, kombu, and wakame and decrease the heat. Add the balls of dough and simmer, uncovered, for 2 hours, until they are firm and slice easily.

Drain the stock from the pot, reserving the stock if not using the seitan straight away. Transfer the seitan to a bowl, add enough cold water to cover, and let sit for about 10 minutes.

Drain and slice seitan into 1/2-inch thick cutlets.

If not using the seitan at this point, store it (sliced or unsliced) in 4 cups of the reserved stock, covered, in the refrigerator for up to 1 month. Alternatively, the cutlets can be frozen (without the stock) for up to 3 months.