Place the flour, almonds and salt in a food processor and process briefly to combine.
Add the butter and pulse until the mixture resembles breadcrumbs.
Add the sugar, lemon zest and egg yolk and mix to form a dough. Add a splash of milk if you think it looks a little dry.
Bring the dough together, flatten into a disk, wrap in cling film and place in the fridge for at least 30 minutes.
Preheat the oven to 375F/190C. Roll out the pastry on a floured surface to about 0.5cm thickness and cut into 12 rounds to line a small bun or tartlet tin. Carefully line the tins with the pastry rounds.
Fill with mincemeat and bake at 375F/190C for 12 minutes.
Remove from the oven and lower the oven temperature to 300F/150C.
Whisk the egg whites until soft peaks form, then keep whisking while gradually adding the sugar, one tablespoon at a time, until stiff peaks form and the meringue is glossy.
Place spoonfuls of the meringue on top of the mincemeat filling, spreading to the edges and then use a butter knife to make small peaks on the top of the pies.
Return to the oven for a further 15 minutes at the lower temperature.
Remove from the oven and leave in the tin until cool.