Preheat the oven to 375°F (190°C). Line a standard loaf pan (8.5 x 4.5 x 2.5 inches) with parchment paper.
In a large mixing bowl, combine the psyllium husk powder, chia seeds, ground flaxseed, ½ tsp. sea salt, sunflower seeds, pumpkin seeds, hemp seeds, sesame seeds, and maple syrup. Add the tahini and 10 fluid ounces (295ml) water, stirring until a thick dough forms.
Transfer the dough to the prepared pan. Use your hands to spread and press it into an even layer.
Bake for 50 minutes, or until the loaf sounds hollow when tapped. If needed, bake for a few more minutes.
Remove from the oven and let sit for a couple of minutes. Lift the loaf out using the parchment paper and transfer it to a cooling rack.
Cool for at least 15 minutes before slicing into 16 pieces.
Note: One serving is one slice.