I make mines in the shaker!
Put 100ml cold/room temp water in shaker - add shake. Shake shake shake
Top up to 350- 400ml mark with boiling water depending how thin you like it and invert the shaker a couple of times, no vigourous shaking, just enough to mix.
I'm curious as to why we can't add hot water straight to the powders, you can't for the soups either ?