Line the loaf pan with parchment paper. Pour milk into small pot and bring it to boil. Set off the pot from the heat and stir in 2 tsp dried lavender. Let the milk to infuse 20 minutes. Set 1 ½ tbsp lavender milk aside for the glaze. Preheat rest of the milk. When milk is about to boil set it off from the heat and add 2 tsp Earl Grey tea leaves into it. Let the milk to infuse for 10 minutes. Sieve milk.
Combine soy yogurt, sugar, and oil and stir until sugar has Dissolved. Measure 1/2 cup of lavender infused tea and milk and mix it with other wet ingredients.
Combine flour, baking powder, baking soda and salt. Sieve flour mixture twice. Grind 1 tsp Earl Grey tea leaves and 2 tsp lavender to a fine powder. Add tea and lavender to flour mixture.
Add dry ingredients to wet ingredients and combine them by folding. Add potato starch to blueberries and stir until blueberries are coated with flour. Fold blueberries into cake batter.
Pour cake batter into prepared loaf pan. Bake in 350 F for 45-50 minutes or until wooden stick to inserted The cake comes out clean. Let the cake cool 10 minutes in the loaf pan and then transfer it to cooling rack. Let it cool completely.
Glaze: Mix powder sugar to reserved lavender milk. The consistency shouldnt be thick but pourable. Smash blueberries and few drops of water with fork. Add couple of drops of blueberry juice extracted to glaze and stir to combine. Spoon glaze over cooled cake and top with fresh blueberries.