Preheat your oven to 175°C (350°F). Line an 8" loaf tin with parchment paper and set it aside.
Add the loose-leaf chai tea to a cup and add 6 tablespoons of boiling water. Cover the cup and allow the tea to steep for 10-15 minutes.
Prepare the chia egg by mixing the chia seeds and 2 ½ tablespoons water and allowing them to sit and soak for at least 5 minutes.
To make the vegan "buttermilk" add the soy milk and apple cider vinegar to a small bowl, stir and allow to sit for 10 minutes.
Pass the chai tea through a sieve to separate the liquid and add it to a large bowl along with the prepared chia egg, vegan buttermilk mixture, and the remaining wet ingredients. Set aside.
Add all of the dry ingredients to a separate bowl and whisk to make sure everything is evenly mixed.
Add the dry ingredients to the wet ingredients in approximately 3-4 increments, gently folding the mixture each time. Be careful not to over-mix, a few pockets of the flour are fine.
Add the cake batter to the prepared loaf pan and bake for 50-55 mins. Check the cake is ready by inserting a knife or toothpick into it, which should come out clean.
Allow the cake to cool in the pan for about 10 minutes before transferring it to a cooling rack.
Meanwhile, prepare the glaze by adding the ingredients to a bowl and whisking until smooth.
Once the cake has cooled, place a sheet of parchment paper under the cooling rack to catch any icing. Pour the glaze on top of the cake, add more or less depending on your taste. Slice and serve.
Store this cake in an airtight container at room temperature.