In a large bowl, whisk together the gluten, nutritional yeast, and poultry seasoning.
In a separate bowl, whisk together the water, ketchup, and lemon juice until well combined.
Add the wet mixture to the dry, and mix together with a fork until well combined. Knead with your hands for about 4 minutes, until a thick elastic dough forms.
In a large saucepan or pot, combine the broth, soy sauce, and garlic. Bring to a boil. Cut the dough in half and place both halves in the saucepan. Return to a boil, then reduce to a simmer. Partially cover the pot so that the lid allows steam to escape, and simmer for 30 minutes. Rotate the pieces of dough, flipping them over. Partially cover and simmer for an additional 30 minutes. Uncover, remove from the heat, and let the dough cool completely in the broth.
Seitan can be stored in the broth, covered, and kept in the refrigerator for up to 10 days. It can also be stored in a sealed container (with the brotin the freezer for up to 6 months. Thaw overnight in the refrigerator.