Start by grating the large head of cauliflower using a grater or food processor until it resembles rice grains. This will be the base of your dish.
In a large skillet, heat the avocado oil over medium heat. Once hot, add the chopped yellow onion and sauté for about 3-4 minutes until it's translucent. Then, add the minced garlic and chopped jalapeño, cooking for another 2 minutes until fragrant.
Stir in the grated cauliflower and cook for about 5-7 minutes, stirring occasionally, until it becomes tender but not mushy.
Add the tightly packed kale leaves to the skillet, mixing them in until they begin to wilt. Then, pour in the can of diced tomatoes, along with any juices, and stir to combine.
Sprinkle in the kosher salt and chili powder. Taste and adjust seasoning as needed, allowing the mixture to simmer for an additional 5 minutes to let the flavors meld together.
Once everything is well combined and heated through, serve your Spanish Cauliflower Rice with Kale immediately. For an extra touch, top with cherry or grape tomatoes for added color and flavor.