Boil the potato chunks for 5 minutes in a large saucepan. Add the cauliflower florets and diced onions, and cook for a further 3-4 minutes until both potatoes and cauliflower are just cooked through. Drain and set aside.
Add the curly kale to a blender or food processor along with the garlic, almonds, olive oil, lemon and parsley, and blitz until finely chopped. (For this recipe I prefer my pesto just 'chopped' rather than a smooth sauce, but the consistency is up to you). Add the soya/nut milk and pulse until combined.
Take a large bowl and add the potato and cauliflower, breaking up the cauliflower florets into small-ish chunks. Pour over the kale pesto and mix together until fully combined.
Grease a 12-hole muffin tin, (I use cooking spray for this). On a floured surface, roll out the pastry to about the thickness of a £1 coin, and cut out 12 large circles to line each hole of the muffin tin. Re-roll the offcuts, and cut out 12 smaller circles which will form the lids.
Fill each case with the potato and cauliflower mixture, (pack it in really tightly, it won't expand or leak during cooking!), and then brush the edges of each lid with a little water and stick down to the rim of the pies, crimping with a fork to create a good seal. Make four little holes in a cross pattern on the lid of each pie with a sharp knife.
Brush the lids of each pie with plant milk, then spray with cooking spray (if you have some handy). Bake for 35-40 minutes until deeply golden brown on top. Leave to cool in the tin, then remove the pies carefully. These can be served either hot or cold.