Gather and prepare your spices: lightly crush cardamom pods to release their oils.

Toast the spices: add cinnamon, cloves, peppercorns, star anise, and cardamom pods to a dry medium saucepan over medium heat and toast for about 1 minute until fragrant, stirring constantly.

Add ginger and water: pour in 3 cups water and add sliced ginger, bring to a boil, then reduce heat to medium-low and simmer uncovered for about 8 minutes.

Steep the tea: remove the pan from heat, add tea bags or loose tea, and steep for 3 to 4 minutes without oversteeping.

Sweeten the concentrate: remove the tea bags, stir in honey until dissolved, and add vanilla extract if using.

Strain the concentrate: pour mixture through a fine mesh strainer into a bowl, pressing gently to extract all liquid, then strain again through a coffee filter or cheesecloth for extra smoothness.

Cool and bottle: let concentrate cool to room temperature (about 20 minutes), then transfer to glass bottles or jars and label with the date.

Refrigerate the concentrate: store in the refrigerator immediately for up to 4 weeks before use.