Place sunflower seeds in a bowl; cover with cool, filtered water. Cover and refrigerate for at least 1 hour or up to overnight. Drain.
In a food processor, combine sunflower seeds, lime juice, salt and water. Puree until sunflower seeds have turned into a loose paste, scraping down sides of the bowl as needed. Add avocado and cilantro; puree until smooth. Add probiotic powder; blend until mixed well. Transfer to a serving bowl. Garnish with sea salt flakes and serve immediately, or cover and refrigerate for up to three days.