In a large 6-quart dutch oven, saute the medium diced onion, 1 1/2 cups of celery, and 1 1/2 cups of carrots in 3-4 tbsp of vegetable broth over medium heat until the vegetables are soft.
Once the vegetables have softened slightly, add 8 oz of minced mushrooms and 3 minced garlic cloves, mix the vegetables together and let it cook for 2-3 minutes.
Add the 28 oz can of fire-roasted tomatoes (with the juice), 2 tbsp of tomato paste, 1 tbsp of smoked paprika, 1 tsp of dried oregano, 1/2 tsp of crushed red pepper flakes, 2 bay leaves, 1/2 tsp of salt, and 1/2 tsp of black pepper to the soup. Mix everything together and let it cook for 5 minutes to allow the flavors to meld.
Add the 4 cups of vegetable broth, 1 cup of water, 6 cups of cooked black-eyed peas, and 10 oz of frozen collard greens to the pot. Bring the soup to a low simmer and then reduce the heat to medium. Let the soup cook for 10-15 minutes or until the vegetables have softened to your desired consistency.
Next, you’re going to add the sliced vegan sausage to the soup. You have two options: You can slice the vegan sausage and add it directly to the soup to warm it up. Or you can saute the sliced vegan sausage in a little bit of oil in a separate pan until each slice has a little bit of color and crispy edges, and then add the cooked sausage to the soup.
Lastly, stir the soup to mix the sausage in and let it cook for 5 more minutes or until the sausage slices are hot all the way through. Garnish each bowl of soup with freshly ground black pepper or crushed red pepper flakes.