How to Make It
Crush peppercorns, cardamom, and cloves with the back of a knife or a mortar and pestle.
Toast crushed spices with fennel seeds in a large saucepan over medium, stirring frequently, until fragrant and lightly golden, 3 to 4 minutes. Add 3 cups water and ginger and bring to a boil. Remove from heat. Add tea bags and let steep for 5 minutes. Remove tea bags, gently squeezing to release excess water; discard bags.
Stir in honey and vanilla and let stand for 1 hour. Strain and discard solids.
Mix 1 part milk with 1½ parts concentrate. Serve hot or cold. Concentrate keeps in an airtight container in the refrigerator for up to 2 weeks.