First, you have to soak the sunflower seeds. The quickest method is by covering them with boiling water for 20 minutes. If you prefer, you can cover them with cold water for 6-8 hours instead.
Drain and rinse sunflower seeds. If you are using the hot water method to soak your seeds, it's important to ensure they are rinsed under cold water so they are not hot when you add them to the blender/food processor as it will change the consistency of the ricotta.
Add the sunflower seeds to a high-powered blender or food processor. Add water, nutritional yeast, lemon juice, salt and apple cider vinegar to the blender. Blend on high until sunflower seeds have been fully blended and no visible chunks of the seeds remain, stopping to scrape down the sides as needed. You can add 1-2 tablespoons more water if needed and blend again. The final product should be creamy with the consistency resembling traditional ricotta. Be careful not to overblend or the consistency will become paste-like.
Transfer mixture to a large bowl and stir in chopped basil, black pepper and garlic powder. You can use the cheese right away but if you have time, I suggest refrigerating it for at least one hour to infuse the flavors.