Transfer the lamb to a carving board and cover loosely with foil. Strain the braising liquid into a medium saucepan and skim off the fat. Boil over high heat until reduced to 4 cups, about 30 minutes. Add the olives, cherries and red wine and simmer over moderate heat for 3 minutes. Whisk some of the braising liquid into the flour paste until smooth, then whisk the paste into the simmering sauce and cook over low heat, stirring occasionally, until no floury taste remains, about 10 minutes. Season with salt and pepper. Discard the strings and carve the lamb in thick slices. Serve with the sauce and the endives.