Soak the raisins (if using) in a just enough warm water (from a kettle, not a tap) to cover them, while you prep the other ingredients.
Melt the coconut oil in a small saucepan over low-medium heat. Add the orange zest and let infuse for a couple of minutes. Stir in the maple syrup, tahini and vanilla, and mix until smooth and glossy.
Combine all of the dry ingredients, except for the raisins, in a large bowl. Fold to combine.
Pour the wet mixture into the dry ingredients, and mix thoroughly until evenly coated. Drain the soaking raisins (discard the water) and fold into them into the granola mixture.
Divide the mixture in half and spread out evenly onto two, parchment-lined baking sheets, pressing firmly into a slab (this helps create clumps!). Let sit 10 minutes, as this hydrates the high-fibre ingredients.
While the granola is hydrating, preheat oven to 300°F / 150°C. Line two baking sheets with parchment paper.
Place in the oven and bake for 25 minutes, flip once carefully to maintain the clusters, and bake for another 15 minutes until golden and fragrant.
Turn the oven off, and leave granola inside for 20–30 minutes, which gently will dry everything out without cooking it anymore (you only need to do this if the granola isn’t fully dry). Cool completely without disturbing, then break into clusters and transfer to a glass container with an airtight lid. Store at room temperature for up to one month. Say thank you and enjoy!