If baking: Preheat the oven 350°F.
Add in wet ingredients and spices: Drain the tofu but do not press it; the liquid is figured into the recipe. Break into a few pieces and add to a food processor along with liquid smoke, soy sauce (or bouillon paste), and olive oil. Also add in tapioca starch and seasonings (nutritional yeast, onion powder, garlic powder, paprika, salt, and pepper). Process into a smooth paste, scraping down the sides of the bowl as needed to incorporate everything evenly.
Form the dough: Add in vital wheat gluten and run the food processor to combine all ingredients and knead the dough. The dough will go through a few phases: first it will come together; then it may appear to crumble apart. Keep processing and eventually the gluten will develop, and it will come together into a firm dough again. If it's hard on your food processor, you can knead half of the dough at a time and then piece it back together afterward.
Knead: The dough should be firm enough that it "cleans" the sides of the bowl — i.e., it should not be so wet that it sticks to the container. If it does, sprinkle in vital wheat gluten 1 tablespoon at a time, processing to combine between additions, until a firm dough is achieved.
Shape & wrap: Remove the dough to a clean surface. Knead it 2-3 times, then shape it into a log. I like to first wrap the seitan in a layer of parchment, followed by a layer of aluminum foil. You can wrap it directly in aluminum if you feel comfortable doing so. Twist off the ends of the foil like a Tootsie roll to seal it in. Make sure the edges of foil overlap each other by at least a few inches, otherwise the loaf might burst out of the seam as it expands during the cooking process.
Oven Cooking Instructions: Place the wrapped loaf on a baking tray. Cook in the preheated 350°F for a total of 1 hour. I like to rotate the loaf by 90° every 15 minutes so that a new section is on the bottom each time. This prevents the bottom of the loaf from getting overly dark or dry.
Instant Pot Cooking Instructions: Add 1 cup of water to the Instant Pot and place a rack to keep the seitan log from touching the bottom. The loaf can be wrapped in foil as directed above, or in several layers of cheesecloth secured with twine. Place the seitan on the rack. Put on the lid, set the valve to Sealing, and pressure cook on High for 1 hour. Allow to release naturally for 15 minutes before removing the seitan.
Cool fully: When the loaf is done cooking, do not unwrap it. Allow it to cool on the counter, then place it in the fridge to chill for a few hours or overnight. (It can be eaten while still warm, but the texture improves and it is easier to slice when chilled, especially if you're going for thin deli slices.)