Rinse the rice with cool water 3 - 4 times until the water is clear. Transfer to a pot with the lime zest, water and salt.
Bring to a boil, then place the lid on the pot and reduce the heat to low. Allow to gently simmer for 12 minutes. Remove from the heat, do not open, and allow to steam for 10 minutes. Remove the lid, fluff with a fork and add the lime juice, vegan butter and cilantro. Mix.
Meanwhile, prepare the taco meat. Grate the tofu with the large holes in a box grater. Heat one tablespoon of oil in a large pan and fry the onion until soft then add the garlic and fry for another 30 seconds.
Add the tofu and the second tablespoon of oil. Raise the heat to medium high and fry the tofu, stirring occasionally, until golden brown and crispy. Add the taco seasoning and fry for another 30 seconds to bring out the flavor. Finally add the tomato sauce and cook for about 20 seconds until heated through.
Assemble four bowls with a base of rice and top with piles of black beans, taco meat, lettuce, tomato, corn, and avocado. Season the vegetables and beans with a pinch of salt. Dollop over your salsa or serve the salsa on the side to add as you eat.