In a large mixing bowl, add in the egg whites and sugar. Whisk vigorously to break apart the egg whites. Pour in the milk while whisking, and whisk until the mixture is well combined.
Place a sieve over a pitcher. Sieve the milk mixture (this makes the pudding silky smooth!) Pour into heat proof bowls that are able to go in the steamer. Cover each bowl with plastic wrap tightly (this prevents the top of the pudding to become dry).
When the water in the steamer has reached to a boil, place the bowls in the steamer and steam over medium heat for 7 minutes with the lid covered. Turn off the heat (don’t open the lid), and let it steam with the residual heat for another 7 minutes. Uncover, let cool slightly, and enjoy!