Put all the ingredients for the mincemeat, except the rum, in a large pan and cook over a low heat, stirring occasionally, for about 10 minutes. Remove from the heat, leave to cool, and then stir in the rum. Cool completely.
For the topping, melt the coconut oil and allow to cool slightly. Mix the flour, semolina and agave together in a bowl. Pour over the melted coconut oil and mix until it combines to form a soft dough. Bring together into a ball and warp in cling film and pop in the freezer for 30 minutes.
For the pastry, put the flour in a mixing bowl and rub in the coconut oil until the mixture resembles coarse breadcrumbs (or whiz in a food processor). Add the agave nectar and just enough cold water to mix to a firm but not dry dough. Shape into a disk and chill for 20 minutes.
Heat the oven to 200°C/fan 180°C. Lightly grease a 23cm x 33cm swiss roll tin.
5. On a lightly floured surface, roll out the pastry to a rectangle, slightly larger than the swiss roll tin, then use it to line the base and sides of the tin.
Spread the mincemeat evenly over the pastry base. Using a coarse grater, grate the topping over the mincemeat. Bake for 25-30 minutes until golden all over
Remove from the oven and leave to cool a little, then slice and serve whilst still warm.