For the matcha soy latte, bring water to a boil and let cool to about 80 °C. Do not mix the matcha with boiling hot water. Pour 1 tablespoon of hot water over the matcha and stir with a matcha whisk to form a paste so that there are no more lumps.
Only then pour the remaining hot water and add agave syrup. Heat soy milk and pour into a tight screw-top jar with grated vanilla and shake firmly, alternatively use a milk frother. When good, firm foam has formed, carefully pour in the tea and serve the matcha soy latte in a tall glass.