In a small dry skillet over medium heat, toast the cardamom pods, whole cloves, peppercorns, and star anise for 1 to 2 minutes until fragrant, shaking the pan so they don't burn. Remove from heat.

Crush spices

Lightly crush the toasted spices together with the cinnamon stick and toasted ginger slices using a mortar and pestle or the flat side of a knife to release oils. You want coarse pieces, not powder.

Simmer concentrate

In a medium saucepan combine 3 cups water, the crushed spice mix, sliced fresh ginger, and brown sugar. Bring to a gentle boil over medium-high heat, then reduce to low and simmer, uncovered, for 10 minutes to infuse.

Add tea

After 10 minutes, add the 3 tablespoons of black tea leaves to the simmering spiced water. Stir, then remove the pot from heat and let steep, covered, for 5 minutes (longer for stronger flavor, up to 7 minutes).

Strain and finish concentrate

Strain the mixture through a fine mesh sieve or cheesecloth into a heatproof container, pressing lightly on solids to extract liquid. Discard solids. Stir in 1 teaspoon vanilla extract. Taste and add up to 1 tablespoon more brown sugar if you prefer sweeter concentrate. This chai concentrate will make about 2 to 2 1/2 cups.

Milk & Finish

Heat and froth milk

For each serving (about 1 cup final): measure 1/2 cup chai concentrate and 1/2 cup whole milk. In a small saucepan, warm the milk over medium-low heat until hot but not boiling (around 150°F / 65°C) for about 3 to 4 minutes. If you like frothed milk, froth the warm milk using a handheld frother, milk steamer, or whisk until velvety microfoam forms.

Assemble chai latte

Pour 1/2 cup warmed chai concentrate into a mug, add 1/2 cup warmed milk, and stir gently to combine. Taste and add the optional additional sweetener (up to 1 tsp) if desired.

Garnish and serve

Dust the top with a light sprinkle of ground cinnamon. Serve immediately. Store any leftover concentrate refrigerated in a sealed container for up to 5 days; reheat and combine with warmed milk when ready to serve.