Soak the TVP or soy chunks or curls in hot water for 30 minutes. Drain.
Mix the flour with salt and pepper and half the herbs. Dredge the TVP chunks in the flour. Shake off any excess flour.
Heat all but 1 teaspoon of the vegetable oil in a Dutch oven or a large, heavy-bottomed pot.
Working in batches, if necessary, brown the TVP chunks in the dutch oven in a single layer, being careful not to crowd them.
Remove the soy chunks to a dish lined with a paper towel and set aside. Also reserve any flour remaining from dredging the TVP because we'll use that to thicken the sauce.
Add the remaining teaspoon of oil to the dutch oven and add the onions and garlic. Season with salt and pepper. Saute, stirring frequently, over medium heat until the onions are softened and translucent, about 3-4 minutes.
Add the carrots, celery, potatoes and mushrooms and any remaining flour and stir to mix. Add the Guinness and let the stew come to a boil. Cook until most of the beer has disappeared.
Add the remaining herbs with the TVP chunks and 4 cups of the vegetable stock.
Bring to a boil, lower the heat to a simmer, cover the pot with a lid, and cook for 30 minutes or until the vegetables are very tender and the flavors have melded together. Add more stock or water if the stew looks too dry. I made my stew rather thick because that's how we like it, but you can definitely make it soupier.
Add salt (and/or the tamari or liquid aminos if using) and ground black pepper to taste. Stir in the butter, if using.
Serve hot. Stew always tastes best when it has had some time to stand and the flavors have mixed together, so this is a great dish to make the day before you want to serve it.