Position one of the racks in the middle of the oven, making sure there's enough room for the dutch oven. Preheat it to 400°F (200°C).
Cut the onions, garlic, potatoes, and carrots. The mushrooms can be left whole if they are smaller. Drain and rinse the jackfruit really well. Look through the pieces and remove any seeds you see. It's okay if you don't get them all.
Heat your pot over medium-high heat. Sauté the onions in olive oil until they are slightly browned. Add the garlic and tomato paste to the pot. Stir as the paste spreads and cooks for 1-2 minutes.
Pour in the pomegranate juice or red wine. Deglaze the pot by scraping the bits off of the bottom.
Mix the cornstarch into the soy sauce in a small container until it's smooth. Stir in the soy sauce mixture, bouillon, water, Worcestershire, salt, pepper, and oregano.
Bring the gravy to a boil, then reduce the heat and let it simmer for 3-4 minutes.
Add the potatoes, carrots, mushrooms, jackfruit, and herbs to the pot. Stir everything to coat it in the sauce. Cover the dish and cook it in the oven for 50-60 minutes. Stir halfway through and add a bit more water if it looks like it's drying out.
The pot roast is done when the vegetables are fork-tender. Remove the herb stems and enjoy!