In a large stockpot, add the water, piloncillo, cinnamon sticks, cloves and tamarind paste, and bring to a boil. Drop to a simmer, and stir to completely dissolve the tamarind paste. Simmer for 15 minutes.
Add the apples, pear, raisins and hibiscus flowers, and simmer for 15 minutes, until the fruit is soft and raisins are rehydrated.
Squeeze the remaining liquid out of the cheesecloth packet and discard. Remove the cinnamon sticks and cloves and discard. Stir in the lemon juice and rum.
Ladle the punch between 12 punch glasses, thinly slice 2 lemons, and garnish each glass with a slice.