In a medium saucepan, combine the water, ginger, cinnamon sticks, cloves, cardamom pods, peppercorns, and star anise. Bring to a boil, then reduce heat to low and simmer uncovered for 20 minutes. This slow simmer extracts the heat from the ginger and the oils from the spices.
Remove the saucepan from the heat. Add the black tea (leaves or bags). Cover the pot and let it steep for 5–7 minutes. Do not exceed 8 minutes, or the tea will become overly tannic and bitter.
Stir in the honey (or brown sugar) and the vanilla extract until fully dissolved. Strain the mixture through a fine-mesh sieve into a glass jar or pitcher. Discard the whole spices and tea leaves.
Let the concentrate cool to room temperature, then cover and refrigerate. It will stay fresh and flavorful for up to 2 weeks in the fridge.