You can use a small milk frother in a deep cup, or a sealed shaker with cool liquid. Sift the powder first and avoid sealing hot liquid.
With a frother
Mix a small amount of powder and liquid in a deep cup, keeping the frother head submerged to control splashes. Add the remaining liquid after the concentrate is smooth.
With a shaker
Use cool liquid in a securely closed food-safe shaker. Shake, check the texture and stir again if powder settles. Wash the shaker promptly after use.
Choose the substitute around the vessel
A small milk frother works best when there is enough depth to keep its mixing head in the liquid and control splashes. A broad, shallow dish and a narrow cup create different working conditions. Start with a small concentrate rather than trying to break dry powder apart in a full glass.
A shaker is a different option for cool liquids. Use an appropriate food-safe container with a secure closure. Do not seal hot liquid. After mixing, check for pockets of dry powder and stir again if the drink settles. The tool should solve a preparation problem, not introduce an unnecessary handling risk.
Solve clumps before chasing foam
Sifting and mixing a small base can make the drink easier to control. If clumps remain, address them before adding more liquid. A large amount of foam does not establish that the powder underneath is evenly dispersed.
For a second trial, change one variable: tool, powder portion or liquid amount. If you change all three, you may not know why the result improved. Keep the final serving instructions for the actual product as the reference, particularly when using a blend with ingredients other than tea.
A practical travel routine
Portable powder does not remove the need for clear ingredient and serving information. Keep the original label, use a clean vessel and choose a mixing method appropriate to the liquid temperature. A 5 g stick is a pack format, not a universal instruction to use all of it in one drink.
If you are planning a routine away from home, trial the vessel and tool first. Record the amount that suits your preparation and clean the equipment promptly after use. Convenience is most useful when you can repeat the drink safely and describe what is in it.