Preheat the oven to 400℉. Heat the oil in a large saucepan, on medium-high heat. Add the onion, garlic, and celery, and cook until the onion is soft, about 3 minutes.
Stir in the jackfruit and Bragg's Liquid Aminos, and cook for about a minute. Add the potatoes, carrots, and peas, and stir. Add the nutritional yeast flakes and GF flour, and stir in order to coat the vegetables.
If you are using green beans, parboil them in water until they are tender, and set aside.
Add the vegetable broth, vegan bouillon, almond milk, and herbs, and bring the pot to a boil. Reduce heat to low and simmer until potatoes are just about tender, usually about 10 minutes. Check the seasoning levels and add salt if needed. Add the green beans and stir.
Scoop the filling into a greased 8-inch casserole dish. Top with puff pastry sheet or rolled out pie dough, and flute the edges. Bake the pie for 20-25 minutes, or until the crust is golden and the filling is bubbly.