NIGEL SLATER admits that he finds 'some, if not most, pontificating on wine and food "marriages" somewhat unconvincing'. He gives TIM ATKIN MW one lunchtime to change his mind. The savoury highlight is baked red mullet with preserved lemons, served with 2005 Kaituna Hills Sauvignon Blanc, Malborough (6.79; Marks & Spencer). While the sweetest sweet thing is mincemeat and apple tart with 2003 Mission Hill