In a medium pot, combine the water with the cinnamon, astragalus, ginger, cardamom, peppercorns, star anise, and cloves.
Bring to a boil, covered, and turn the heat down to simmer for 20 minutes.
Turn off the heat and add the dried calendula flowers and tulsi leaves; stir.
Infuse, covered, for 20 minutes, and then strain.
If you prefer sweet chai, add the sugar after straining; stir well.
Let cool, and store the chai concentrate in the refrigerator. Use within 4 days.