To make ketchup, combine the cherries, brown sugar, salt, vinegar, lemon rind, ginger, cinnamon sticks and cayenne pepper in a sauce pan. Bring the mixture to a simmer and cook it until it has thickened - about 15 minutes. Discard the cinnamon sticks and pour the mixture into a food processor. Puree the mixture, then strain it into a small bowl and allow it to cool.
To prepare a marinade for the meat, mix a generous grinding of pepper with the allspice, cloves, lemon juice and brown sugar in a bowl. Put the eye of the loin in a shallow dish and pour marinade over it, rubbing the spices into the meat. Let the lamb marinate at room temp for 1 hour, turning it every 15 minutes.
Remove the lamb from the marinade and cook it for 5-7 minutes on each side, brushing it occasionally with any marinade remaining in the dish. Let the lamb rest for about 5 minutes before slicing it. Serve the ketchup separately.
