Chop the celery, onions, green pepper and quarter the mushrooms. Heat a large pot over medium heat & add 1 tablespoon of oil - add in the vegetables and 1 tablespoon of the seasoning mix. Sauté for about 10 minutes until the vegetables are translucent.
Add in 1 cup of rice to the vegetable medleyand stir to combine well. Increase the heat to high and add the water. When the mixture comes to a boil, turn the heat to cover and reduce the heat to low. Cook for 30 minutes or until the rice is cooked and the water is absorbed.
Drain the can of black beans and rinse well until the water runs clear. Add to a small pan on the stove and place over medium-low heat. Add in the salsa and 1 teaspoon of the seasoning mix. Stir occasionally.
While the rice is cooking prepare your garnishes - then when the rice is done, assemble the tacos and enjoy!