Weigh the 2 flours, ground almonds, icing sugar directly into a good-sized bowl – zeroing the scale each time. Add the salt and mix well.
Add the chilled, vegan butter as cubes, then use a pair of large table knives (one in each hand like scissors) to cut the fat into the flour. When it’s in very small pieces, you can finish off by rubbing it in using just your fingertips you’re looking for the mixture to resemble fine breadcrumbs with no lumps of butter remaining. You can also do it in a food processor - pulse blitz it, but don't overdo it.
Add the cold water (or spirit if using) and mix with a pallet knife to combine. It should come together into a ball fairly easily – it may need just a little more water, but it’s best to avoid this if you can. Form the pastry into a disc – but don't knead it. Place on a piece of grease-proof paper, and cover with a suitably sized bowl. Then refrigerate for about 30 minutes until firm enough to roll out. Don’t leave it too long though or it will become too hard.
Roll the pastry out on a lightly floured cool surface until you have a circle 3cm bigger than the base of a 25cm fluted round tart tin. A loose base tin is best.
If you have a loose base, remove the base, grease it and place a same sized parchment paper circle on it. Place it in the centre & on top of the pastry, and then cut round it.
Carefully remove the edge pieces and free the pastry from the surface using the pallet knife and some flour - so you can slide the base under the pastry circle. This is the most fool proof way. Position the pastry so it perfectly covers the base, then return it to the tart casing.
Take the edge pieces and run them round the edge - so they join the pastry base – they will be more than long enough. Press the pastry into the flutes/corners then cut off the top with the pallet knife.
If you can’t do it this way because you don't have a loose base tart case, you’ll have to attempt to get the pastry into the tin without it breaking or getting mangled – that is a very tricky way to do it.
Prick the base of the pastry all over with a dining fork then place it in the freezer for 20 minutes until solid. Meanwhile preheat the oven to 180°C/160°C fan.
Line the pastry case with a baking parchment circle, then fill sufficiently with ceramic baking beans to keep the sides in place.
Bake for 15 minutes then remove the paper and baking beans and return the pastry case to the oven for a further 5 minutes until pale golden. Remove from the oven and set to one side. If you over cook it now, it will brown too much when cooking with the filling in later.