In a large pan, heat up 2 tablespoons of olive oil on medium high heat. Once the oil is hot, add the yellow onion and cook until translucent and slightly caramelized. It should take about 6-7 minutes.
Add the chopped garlic next and cook for a minute until fragrant.
At this point, you can add the mushrooms. Turn the head down to medium. And cook the mushrooms down. This should take about 6-8 minutes. They will shrink to about half in size.
Once the mushrooms are cooked, stir in the miso paste.
Add the riced cauliflower next and cook for another 2-3 minutes. Add the soy sauce and the rice vinegar.
Next add a handful of spinach and let it wilt. This works best when you cover the pan at this point. Once the first handful is wilted, add another handful and repeat until you have added all the spinach.
Season with salt and red crushed pepper to taste. You really shouldn’t need much salt because the miso and soy sauce both have salt in it. Serve in a large bowl. Garnish with some sesame seeds. You can also top with some Sriracha!