Heat a frying pan over medium low heat. Add olive oil, if desired, and then the onion and garlic, cooking for 5 minutes.
Add the veggies and cook for 20 minutes, stirring often. Add the black beans to the final 5 minutes of cooking.
Meanwhile, make the avocado crema: in a high-powered blender, combine: cashews, boiling water, salt, avocado, lemon, apple cider vinegar, jalapeno, garlic, and cilantro. Blend on high for about a minute.
Plate the spinach, then the veggie mixture, and top with the avocado crema.