Sift the flour, sugar, salt, cornmeal, mixed spice, ground ginger and cinnamon together into a bowl. Cut the butter into small cubes and rub into the flour mixture until the texture resembles fine breadcrumbs. Add the cold water and sour cream and bring together to make a rough dough. Wrap in cling film and chill until firm, about 30 minutes.
Caramelized winter fruit
In a heavy based saucepan, mix all of the ingredients for the syrup together. Bring to the boil, and then reduce the heat and leave to simmer. Meanwhile halve the kumquats, cut the persimmon into segments, peel the apples and using a Parisian scoop cut apples into small balls.
In a separate pan of boiling water blanch the kumquats until the rinds have softened slightly, about 3 minutes, drain and reserve.
Add the dried apricots to the simmering syrup, cook for five minutes, then add the prunes and kumquats, cook for a further two minutes then add the apple balls and dried cranberries. Continue to cook until the fruit is tender, about three to five minutes.
Remove pan from the heat and allow to cool. Drain off the fruit and reserve. Discard whole spices. Return the syrup to the heat and reduce until a syrup consistency is achieved.
Cream together the butter, brown sugar and orange zest. Gradually add in the eggs blending well between each addition. Sieve the flour, add the ginger, mixed spiced, cinnamon and ground almonds and fold into the butter mixture. Refrigerate until required.
Preheat the oven to 190˚C. On a floured worktop, roll out the chilled pastry dough until a thickness of 3 cm is achieved. Cut into a 30 cm circle. Line a roasting pan with baking parchment, place a 25 cm metal ring on top and arrange pastry centrally in the ring. Brush egg whites around the inner edges of the pastry. Transfer the gingerbread mixture into the pastry and top with the poached fruits, reserving a small selection for decoration. Pinch together the edges of the pastry dough ensuring the middle is left exposed. Brush with egg white, sprinkle with caster sugar and bake until golden brown, about 25 minutes. About 5 minutes before the tart is fully cooked brush with remaining syrup and arrange reserved fruit on top of tart.
Remove from the oven and allow to stand for 5 minutes to cool slightly, run a knife around the edge of the metal ring to loosen then remove.