Add ALL the ingredients EXCEPT the vital wheat gluten to a food processor and process until mostly smooth. Then add the vital wheat gluten, half at a time and pulse until mostly combined. (It doesn't have to be perfect.)
Transfer the mixture to a clean cutting board or other clean surface. Then knead the dough with your hands for 2-3 minutes. Shape it into a log that measures approx. 4 inches wide and 8 inches long.
Snugly wrap it with parchment paper and then aluminum foil and twist the ends to secure it. (See process shots above for reference.) Then choose ONE cooking method below.
Instant Pot Instructions
Add a cup of water to the bottom of your Instant Pot and place the trivet on top. Then place your wrapped vegan roast on the trivet. Close the lid, ensure the valve is in the sealing position, and set it to "steam" for 60 minutes. Let the pot naturally release and then open it once safe to do so. (It will take approx. 10-12 minutes to naturally release.) Transfer your roast to a cutting board and LET IT REST for 10 minutes before slicing.
Baking Instructions
Preheat the oven to 375℉/190℃ and place the wrapped seitan roast on a baking sheet. Bake it on the center rack for 45 minutes. Then flip it over and bake it for an additional 45 minutes. Remove it from the oven and LET IT REST for 10 minutes before slicing.
Steaming Instructions
Bring a large pot with a couple of inches of water to boil and place your steamer basket inside. Make sure the basket is not touching the water. Once boiling, reduce the heat to maintain a low boil/simmer, place the wrapped vegan roast inside, and put the lid on top. Steam for 35 minutes, then flip it and steam an additional 35-45 minutes. Check your water level every so often and add hot water as needed. Once cooked, transfer your vegan roast to a cutting board and LET IT REST for 10 minutes before slicing.
Notes
Weigh the vital wheat gluten for the most accurate results. If you must measure using cups, make sure to spoon and level the flour. DO NOT scoop from the bag or you'll end up with more than needed.
Make sure to use a very flavourful and salty broth since there's no other salt added. If you only have low-sodium broth on hand, add ½-1 teaspoon of salt.
To test for doneness: Gently peel back the foil, the seitan roast should appear smooth. Give it a poke with your finger or tongs to test firmness. (Careful it will be HOT!) It should feel firm but still give a little to pressure. It will continue to firm up as it cools.
Leftovers will keep refrigerated for up to 5 days. Or freeze the vegan roast in an airtight freezer-safe container for up to 3 months. You may freeze it whole, or in slices.