To make the pastry, place the flour, salt, turmeric and curry powder in a food processor and pulse to combine. Add the cold, diced butter and blend until it resembles fine breadcrumbs.
With the motor running, gradually drizzle in the cold water until it starts to clump together into a dough. You may not need all of the water.
Bring the dough together with your hands and shape into a disc. Cover and place in the fridge for at least half an hour.
To make the filling, place the coconut oil in a large pan over a low heat. Add the onion and cook for about 10 minutes, stirring often, until it is soft.
Add the sweet potato, carrot, butternut squash, cabbage, tomatoes, peas, sweetcorn and broad beans and cook for another 10 minutes, stirring often, until the vegetables have started to soften.
Add the garlic, scotch bonnet, spring onions, allspice, ginger, cinnamon, cumin, paprika, turmeric, thyme, salt and white pepper and cook for another minute.
Add the coconut milk and simmer for 5-10 minutes until the vegetables are tender and the liquid has reduced. Allow to cool then refrigerate until cold.
Once both the filling and pastry are cold, divide the disc of pastry into 8 even pieces and roll each one into a ball.
On a lightly floured surface, roll each ball out into a circle about 3mm thick. Cut round an upturned approx 16cm/6in round plate or saucer with a sharp knife to get a neat circle of dough.
Place a couple of heaped spoonfuls of the filling on one side of the circle, be careful not to add too much or you won't be able to seal the patty.
Brush a little water around the rim of the pastry and fold it over the filling. Press the edges together to seal, then crimp the edge with the tines of a fork. Cut a little slit in the top of the patty for steam to escape.
Once you have rolled out and shaped all 8 of your balls of dough, gather together the trimmings and divide them into two balls. Roll out and shape as before to make two more patties. You might have a bit of filling left over.
Place the patties on a couple of baking sheets lined with baking parchment and refrigerate for half an hour (or freeze for 20 mins).
Meanwhile, preheat the oven to 200°C/180°fan/400°F/gas mark 6. Brush the tops of the chilled patties with a little dairy free milk (I used soy) then bake for 25-30 minutes until golden and bubbling.
Set aside to cool for about 10 minutes before serving. Store any leftovers in the fridge for up to 3 days.