Mix the dry ingredients in a large bowl.
Mix the wet ingredients and pour over the dry ingredients. Knead everything to a smooth dough for 2-3 minutes. Cut the dough into 4 pieces of approximately the same size and let them rest for 10 minutes.
Mix the broth, bring to a boil in a saucepan and switch down temperature so that it is boiling just a little. Form and stretch the seitan pices into very thin steaks and simmer them for 15 minutes. Take them out, let them cool and gently squeeze out the excess liquid. Keep the broth for later use.
Mix the marinade. Let the seitan steaks soak in the marinade for a few hours, preferably overnight.