Preheat your oven to 400°F (200°C).
In a large bowl, stand mixer, or food processor, mix together the vegetable stock (or water), tamari, coriander, poultry seasoning, nutritional yeast, chickpea flour, and vital wheat gluten until fully combined. Let the dough rest and hydrate for 10 minutes.
Place the seitan dough into a food processor fitted with an S-blade, and process it for 2 full minutes to agitate the gluten.
Using wet hands, compress your stuffing into a 4-5 inch (10-12 cm) wide log shape, and then cover it completely, on all sides (including the bottom), in the seitan dough. Place the stuffed seitan onto a lightly oiled parchment-lined baking sheet.
Bake at 400°F (200°C) for 20-25 minutes until the outside feels just slightly firm to the touch. Remove from the oven and set aside.
Bring the water, bouillon paste, and tamari to a boil in a Dutch oven or thick-bottomed pot. Carefully add the baked seitan into the pot, and immediately reduce to a low simmer, cover the pot, and cook for 40 minutes.
Lower your oven temperature to 350°F (175°C). Carefully drain your seitan in a colander.
Rehydrate two sheets of yuba skin in water until pliable. Squeeze out excess water.
Lay one yuba sheet on a lightly oiled parchment-lined baking sheet. Place the drained stuffed seitan onto the yuba.
Wrap the vegan turkey in the yuba skin, covering it completely. Use the second yuba sheet from the top, wrapping under the sides and bottom of the seitan turkey to cover any visible seams.
Either in a blender or using the tines of a fork in a small bowl, mix together the brown sugar, mustard, cider vinegar, apple cider, pepper, thyme, and olive oil to form the basting liquid.
Brush the seitan turkey with the basting liquid, reserving some of it for a second basting, and roast at 350°F (175°C) for 20-25 minutes. Brush with additional basting liquid at the halfway point, and again just a couple of minutes before removing it from the oven.
Garnish the roasted vegan turkey with chopped fresh herbs and serve it sliced with a gravy of your choice.