Heat the oil in a large saute pan (you need one with a lid), once warm add the nopales and sprinkle the salt over them. Saute until they have begun to softened and released a lot of their viscous liquid. This should take about 8 minutes.
Next add the onion, mushrooms and garlic and saute until they too have softened. Next add the quinoa to the pan and give it a good stir., then add the chopped tomatoes and again stir until well combined. Carefully pour in the vegetable broth, turn heat up and simmer until it begins to boil. Lower heat to low, cover the pan and simmer until the quinoa is cooked through and nearly all of the liquid has been absorbed. If needed you may add a little bit more vegetable broth to help cook further.
Allow to cool slightly and serve as a main dish for 2 people or 4 side servings. Enjoy!
*If you'd like you can give this dish a touch of heat by adding a small serrano pepper or half of a jalapeno. You would add it when the onion is added to the pan.