Preheat the oven to 375 degrees.
Toss the mushrooms (you should have about 8 cups total) with the garlic mojo, 1 teaspoon salt and the epazote. (If you're using cilantro, wait until the mushrooms are done roasting before adding). Scrape into a 13 x 9-inch baking dish and wrap tightly with foil. Place in the oven and roast for 10 minutes. Remove the foil and continue roasting for another 40 minutes, or until the mushrooms are golden brown, and the mushroom liquid has evaporated. Remove from the oven, and if you're using cilantro, stir it in at this point. Cover and keep warm. Raise the oven temperature to 400 degrees.
Heat a 10-inch skillet over medium with 2 tablespoons oil. Once the oil is hot, stir in the garlic and cook for 1 minute until it just begins to brown. Add the beans and their liquid along with 1/2 teaspoon salt. As the beans come to a simmer, mash them into a smooth paste with an old fashioned potato masher or the back of a large cooking spoon. Cook, stirring nearly constantly, until the consistency of very soft mashed potatoes, about 10 minutes. Cover and keep so that the beans stay soft and moist.
Slice the rolls open lengthwise and using your fingers or a spoon, scrape out some of the soft bread in the center of each half, making a small hollow. Spread the tops with goat cheese and set aside. Spread 2 tablespoons of the black beans on the bottom half of each of the rolls. Place on a rimmed baking sheet and spoon on the mushrooms. Set the baking sheet on the middle rack and bake for 5 minutes until the bread crisps and the mushrooms are warm. Carefully remove the baking sheet, and top each roll with a handful of arugula leaves and a drizzle of salsa. Cover each torta with the goat cheese half, and place back in the oven for another few minutes or until the bread crisps and the goat cheese is warm. It's now time to enjoy your fabulous torta.