In a large bowl, mix together the sesame seeds, pumpkin seeds, chia seeds, zaatar, psyllium husk, and sea salt. Stir well to combine, then add the water. Cover the bowl and set aside for 5 minutes, allowing the mixture to thicken considerably.
Preheat the oven to 150°C / 300°F with a rack in the center.
Line 2 to 4 large baking sheets with parchment paper (you may need more if using smaller sheets). Brush the parchment lightly with olive oil to prevent the crackers from sticking after baking.
Spread the mixture onto the baking sheet using the back of a spoon, pressing it down into a single, even layer that is paper-thin. Place it in the oven and bake for 45 minutes to 1 hour, or until the seeds turn a beautiful golden color. The exact time will depend on the size of your baking sheet; smaller sheets will bake faster.
Remove from the oven, and while the paper-thin sesame seed sheet is still warm, carefully peel off the parchment paper underneath. Leave it to cool down completely. To store, wrap tightly with cling film and keep in a cool, dry place away from air drafts—they will stay perfectly crispy for up to 2 weeks. Enjoy!
Serve it alongside a creamy labneh dip, or pair it with whatever your heart desires!