To make the seitan

1. Combine the flours together. Then, in a separate bowl, whisk together the rest of the seitan ingredients, then add it to the flour mixture. Knead in a Kitchen Aid mixer using the dough hook attachment or knead with your hands for one minute to form a cohesive ball of dough. Tear off small, jagged skewer-sized pieces and place to the side. (The pieces will double in size during simmering time.)

To make the simmering broth

1. Combine the broth, garlic, soy sauce, agave and ice cubes in a medium-sized pot. Do not turn on the heat yet—you want the broth to be very cold when you add the seitan to it.
2. Next, place enough olive oil to cover the bottom of a cast iron pan or any other non-stick pan. Heat the oil over medium heat. Place the seitan chunks in the pan and allow to brown on both sides. Transfer to a plate to cool.
3. Drop the cooled seitan chunks into the broth. Bring to a very small simmer, then maintain that heat for about 45 minutes. Cover with a lid that allows some steam to escape during cooking time. Do not allow the broth to boil at any time—it will affect the texture, making it spongy.

To make the marinade

1. Add all of the marinade ingredients in a saucepan. Toss the seitan chunks in the marinade, then thread onto metal or wood skewers. (If you are using wood skewers, soak them in water first for about an hour to prevent them from burning.)
2. Now bring the leftover marinade to a small boil in a small saucepan, reduce the heat, and allow to simmer and thicken for 7-10 minutes.
3. Grill the seitan, turning and basting often with the reduced marinade. Serve immediately, drizzling any extra sauce over the top.