Preheat oven to 350° Fahrenheit.
Make the enchilada sauce by whisking together olive oil and corn starch in a large skillet over medium heat, until starch has fully dissolved.
Add in the chili powder, cumin, salt, onion powder, and garlic powder, cook for 2 minutes.
Pour in apple cider vinegar, tomato paste, and vegetable broth, then reduce heat to low and simmer for 5 minutes or until sauce has thickened.
Prepare the filling by heating olive oil in a separate large skillet over medium heat. Add in mushrooms, bell pepper, and yellow onion, cook for 3-5 minutes or until veggies are tender.
Add in black beans, garlic powder, cumin, paprika, salt, and ½ cup of enchilada sauce you made earlier. Stir and cook for 2 minutes, then remove from heat.
Roll enchiladas by placing ¼ cup of filling mixture in the center of each tortilla, ten rolling tortilla around filling to seal. Repeat this process until all 8 tortillas are stuffed and rolled.
Spoon half homemade enchilada sauce into the bottom of a large baking dish. Then, place all 8 enchiladas on top of sauce with the seam side facing down.
Top with remaining enchilada sauce, then vegan cashew cheese if using. Bake for 20-25 minutes or until bubbly.