Combine the hibiscus flowers, sugar, allspice, peppercorns, cinnamon sticks, cloves and orange zest in a medium pot with 2 quarts water. Bring to a simmer over medium heat. Keep at a bare simmer 10 minutes, and then strain. Serve hot, or cool to room temperature over ice, and garnish with a cinnamon stick or orange slice. Add 1 cup tequila to the whole punch, or 1 shot to each individual glass, if desired.