Method (blueberry lemon filling)

1. Add the blueberries into a medium-sized saucepan and sprinkle over the sugar, corn starch / corn flour, lemon juice and lemon zest.
2. Place on top of the hob over a medium to high heat and bring to the boil. This will take around 5-8 minutes. Keep stirring with a heatproof spatula or wooden spoon to prevent the mixture from sticking and burning. It will start to turn thick. Once thick, remove from the heat and allow to cool for a few minutes before using. As it cools, it will thicken up even more and turn into a jelly-like.
3. Store in a sealed container in the fridge until you’re ready to use it. Alternatively, you can pour the filling directly into the pastry and bake.

Method (pastry)

1. You will need a large pie dish. Lightly grease it with dairy-free block butter and a sprinkle of flour. (I used a 9-inch deep dish.) Alternatively, you can use a tart tin and grease it using the same method.
2. In a medium sized bowl, sift in the flour, salt, sugar and lemon zest. Stir to combine, set aside.
3. Cut the butter into small cubes and place into the freezer for approximately 5-8 minutes. It’s important the butter stays as cold as possible when making pastry dough!
4. Add cubes of cold butter into the flour mixture, one at a time. Use a fork to break up the butter.
5. Use your fingertips to gently rub the butter into the flour mixture until it resembles bread-crumbs.
6. Add in the ice cold water a tablespoon at a time until the dough comes together. It’s important you don’t over-knead the dough as you will loosen the flakiness.
7. Wrap the dough in greaseproof paper and place into the fridge for 40min – 1 hour. This makes it easier to roll out, less sticky to handle and also gives the dough time to chill again.
8. Remove the dough from the fridge and allow to sit at room temperature for 5 minutes.
9. Slice the dough in half so you have 2 balls of dough. Wrap one ball of dough up and place back into the fridge for later (this will be for the lattice detail).
10. Flour a clean work-surface and rolling pin. Roll out one of the dough portions into a 12 inch circle (around 1/8 inch thick), a few inches bigger than your pie dish / tin. Alternatively, you can roll the dough out between two pieces of greaseproof paper. Make sure the dough isn’t sticking to the work-surface or paper, add more flour if necessary.
11. Check the size by inverting a pie dish over the top of the dough. Look for around a 1-inch edge around the pie dish. To transfer the dough to the dish, starting at one end, roll the dough around a floured rolling pin, then carefully unroll over the dish.
12. Gently press the dough down into dish so that it lines the bottom and sides of the dish. (Being careful not to stretch the dough).
13. Use a sharp knife to trim off any excess.
14. Use your fingers to crimp the edges of the pastry (optional).
15. Optional step: you can blind bake the pastry with baking beans if you fancy. I like to partially blind bake the crust for 8 minutes with baking beans, as this prevents a soggy bottom. To blind bake, line the dough with grease proof paper and pour in baking beans or rice. Pop the crust into the middle of a oven set to 170°C fan and bake for 8 minute. Remove from the oven and continue with the next step.
16. Spoon the berry filling into the pie, enough to fill the pie dish 1/2 full. Set aside.
17. Remove the second pastry ball from the fridge and allow to come down to room temperature for 5 minutes.
18. Preheat oven to 170°C fan.
19. Add the excess dough to the already chilled dough. Flour a clean worktop and rolling pin. Roll out the dough until 1/8 inch thick. Use a pizza roller, sharp knife or pastry cutter, slice the dough into even strips (depending on how thick you want the lattice). You can even braid the dough for a decorative detail.
20. Gently pick up the strips and lay 5 vertically over the pie, making sure that they’re evenly spaced out.
21. Carefully fold back the first, third and fifth strips towards you then lay a strip of dough perpendicular to other dough strips. Unfold the first, third and fifth strip over the new strip.
22. Unfold second and fourth strips over the new strip. Repeat until you have a beautiful lattice detail. 
23. With any excess dough, cut out flowers, or any decorative shape you fancy using small cookie cutters. Using some dairy-free milk, stick them on-top of the pie.
24. Brush the entire pastry with dairy-free milk and sprinkle over some more caster sugar. This will ensure that the pie gets a gorgeous golden colour once baked.
25. Place the pie into the middle of the oven and bake for 45 minutes, or until the berry filling is bubbling and the pastry is golden.
26. Remove the pie from the oven and allow to cool down. It will be extremely hot.

Slice with a sharp knife and serve.