Turn off the heat and allow the tea to steep for 30 minutes.
Strain through a fine mesh strainer, pressing the tea pulp with the back of a spoon to extract as much liquid as possible.
Allow the concentrate to cool completely, then transfer to a sealed jar or bottle and refrigerate.
To assemble
To serve, fill a tall glass generously with ice, pour the concentrate to about three-quarters full, and top with milk of your choice.
For extra creaminess, drizzle a tablespoon of condensed milk on top and stir well before drinking.
Notes
Single-Serve Thai Iced Tea: To make a single glass, add 2 tablespoons of Thai Tea Mix to a fine-mesh tea infuser and place the infuser in your teapot or mug. Pour 1 cup of boiling water over the infuser and stir in 2 tablespoons of sugar while the tea is still hot, making sure it dissolves completely. Allow the tea to steep for 15 minutes, then remove the infuser. Let the tea cool to room temperature before assembling your glass as described above. No tea infuser? No problem! Simply bring 1 cup of water to a boil in a small pot, add the Thai Tea Mix and sugar, and stir well. Turn off the heat and let the tea steep for 15 minutes, then strain through a fine mesh strainer into your cup.