This recipe is adapted from The Buddhist Chef.
In a large bowl, combine vital wheat gluten, chickpea flour, nutritional yeast, smoked paprika, dried basil and onion powder. Keep aside.
In another bowl, whisk together ketchup, soy sauce and 1½ cups of hot water.
Add the wet mixture to the dry ingredients and stir until the mixture has a dough-like consistency. Knead for 2 to 3 minutes, adding more vital wheat gluten if the dough is too sticky. Shape into two loaves.
In a large pot, bring the vegetable stock to a boil. Carefully place the seitan loaves in the boiling broth. Cover, return to a boil and reduce heat to low. Continue simmering until firm, turning the seitan over occasionally, for about 1 hour.
Remove from heat and let the seitan cool for 15 minutes in the broth. Remove from broth and slice seitan before serving.