Line a standard standard loaf pan with parchment and set aside. Put sunflower seeds into a food processor or blender and blend until very fine and beginning to look like really thick nut butter (but not quite). Use a spatula to scrape the mixture into the bowl of a stand mixer and add the vanilla and salt.
If you'd like to skip the step of grinding the seeds you can try using sunflower seed butter instead. The texture will be slightly more fudgy but the flavor is very much the same. Simple replace the 2 cups of seeds with 1 cup of the sun butter.