Bring the water to a boil in a small pot.
Steep the black tea in the hot water for 4–5 minutes, then strain out the leaves.
Warm the milk and cream over low heat. Stir in brown sugar, vanilla, and salt until fully dissolved; do not boil.
Fill two glasses with ice and add tapioca pearls if using.
Divide the hot tea between the glasses. Top with the warm milk mixture and stir gently to combine.
Serve immediately. For a hot version, skip the ice and pour the milk mixture directly into mugs of tea.