Sprinkle salt and pepper on both sides of the salmon. Then, heat a large, nonstick skillet with olive oil over medium-high heat. Place the salmon skin side down and cook the salmon for 5 minutes. Then, flip the salmon over and cook it skin side up for an additional 5-6 minutes (note: cook times vary depending on thickness of the salmon). If the salmon is on the thicker side, you may want to place a lid on the skillet, which will help it to cook more quickly.
While the salmon is cooking, whisk all of the sauce ingredients together in a bowl, and also cook the cauliflower rice according to the package instructions.
Once the salmon is cooked, reduce heat to medium-low, then add the garlic and sauté for 1 minute. Reduce the heat to low, and pour the sauce into the skillet. The sauce should thicken rather quickly; once it does, remove skillet from the heat and use a spoon to spoon the sauce over the skillet. (note: if sauce isn't thickening, turn the heat up to medium)
Divide cauliflower rice into bowls, then top it with the cooked salmon and avocado. The last step is to cook the spinach: wipe out the skillet that you cooked the salmon in, then place it back on the top over medium heat. Add spinach, along with a little more oil, and cook until the spinach is wilted, 2-3 minutes.
Top the bowls with green onions and enjoy!