In a small heatproof bowl, combine sugar, matcha powder, vanilla extract, and sea salt. Pour in 1/4 cup of very hot water. Whisk vigorously with a metal whisk until the mixture is smooth, creamy, and lump-free. Set aside.
3 tbsp white sugar, 3 tbsp food-grade matcha powder, ¼ tsp vanilla extract, ⅛ tsp sea salt, ¼ cup very hot water