Grease cake tin and lightly dust with flour, shake off excess.
Preheat oven to 180 deg. C
Cut open tea bags and pour out the dry tea leaves into a coffee grinder or blender dry mill.
Grind to turn into powder. Sieve using a very fine sieve.
In a small bowl mix together warm milk and tea powder, stir well and set aside.
In another bowl sift together flour and baking powder, mix well and set aside.
Place eggs, sugar and vanilla in the bowl of your mixer or any clean bowl, beat until light and fluffy.
Add oil in a steady stream and beat on low speed or if mixing by hand, just continue beating.
Pour in milk and keep mixing.
Add flour and mix well. Scrape down the sides of your bowl.
Pour cake batter into the prepared tin.
Hit cake tin hard 4-5 times on a table to avoid large air bubbles forming inside the cooked cake.
Bake for 30-40 minutes until a skewer inserted into it comes out clean.
Place tin on a cooling rack to cool a bit then remove cake from tin to cool completely. Eat warm or cool.