Heat Olive Oil: In a large skillet, heat the olive oil over medium heat until shimmering.
Sauté Onion and Garlic: Add the chopped onion and minced garlic to the skillet. Sauté for about 2-3 minutes until they are soft and fragrant.
Cook Mushrooms: Stir in the sliced mushrooms and cook for an additional 4-5 minutes, or until they become tender and begin to release their moisture.
Add Cauliflower Rice: Next, add the frozen riced cauliflower and soy sauce. Stir well to combine everything, cooking for about 5 minutes until the cauliflower rice is heated through and tender.
Incorporate Spinach: Finally, add the fresh spinach, stirring until it wilts and becomes bright green, about 2 minutes.
Serve: Taste and adjust seasoning if needed, then serve hot as a delicious and nutritious side dish!