Just made up some chai concentrate. It is delicious! I’ll summarize my method below.
I used a generous tablespoon or so each of black peppercorns, cloves, cardamom, a few cinnamon sticks, and a couple good hunks of dehydrated ginger. I crushed the spices with a mortar and pestle, and simmered in 4 cups water for 10-20 minutes, then added about 3 tablespoons darjeeling tea, removed from the heat, and steeped for about 7 minutes.
To serve one mug, I mixed about 50:50 tea concentrate and hot soymilk, and a generous spoonful of sugar.