Bring the water to a boil. Dissolve the sugar by whisking it into the boiling water, then remove from the heat and add tea bags, star anise, cinnamon sticks, cardamom, and tamarind.
Steep the tea and spices together for 5 minutes, then remove the tea bags and allow the tea and spices to cool down. For faster cooling, transfer to a jar and leave at room temperature until cooled.
Once cooled, store in the refrigerator and steep spices for 2 to 8 hours. Tea will turn cloudy orange.
In the meantime, whisk the sweetened condensed milk until loosened. If using, whisk in the half and half.
Strain the spices out of the tea. Pour the tea into a glass over ice, 1 cup for 1 portion. Pour the whisked milk into the drink, using just over 1 tablespoon per serving.