Pre-heat your oven to 150 C / 300 F / gas mark 2.
Place the silken tofu, bouillon, apple cider vinegar, onion powder, miso paste, garlic powder, celery salt, mixed herbs and pepper into a blender and blitz on high until smooth.
In a large bowl, mix together the vital wheat gluten, chickpea flour, nutritional yeast and rice flour.
Pour the wet ingredients (including the dissolved agar agar) into the dry ingredients in the bowl and mix well until it has formed a dough.
Next, knead the dough (either by hand or using a stand mixer) until it is stretchy and elastic and all of the ingredients are well combined.
Roll the dough out into a rectangle with the longest edge running horizontally in front of you.
Lay the stuffing ingredients down the middle then pull the top edge of the dough over, encasing the stuffing in the dough in one long sausage.
Pinch the ends together to prevent the sausage from coming undone and the stuffing escaping.
Heat a little oil in a large heavy bottomed frying pan, add the sausage to the pan (seam side down) and cook for 5 minutes until it has formed a crust. Roll the sausage around and cook until you have an even crust all over.
In the meantime, add the ingredients for the cooking stock to a large casserole dish.
Lay a cheesecloth out on your counter, place the cooked sausage in the middle and wrap it up, using kitchen twine to seal the parcel.
Place the wrapped sausage into the stock (it should be at least half covered by the stock), add the lid to the casserole dish and cook for 2 hours, flipping it over halfway.
Once cooked, remove from the oven, unwrap and serve sliced while still hot.