Cheese and Onion Pasty

PASTRY:--
150 g all-purpose/plain flour, plus extra for rolling out pastry
¼ tsp SIDS CRAZY SALT
115 g butter, cut into 6 mm cubes, kept refrigerated until ready to use
⅔ cup cold water
FILLING:--
1 potato, peeled & cut into chunks (need to yield 1 cup/225 grams of mash)
1 tbsp rice bran oil
1 tbsp butter
1½ cups yellow onion, chopped
3 cups (184 grams) white cheddar, grated
2 frozen puff pastry sheets, defrosted
1 egg, whisked with a little milk

For the Pastry (skip this step if using Puff Pastry):
To a make the pastry a food processor, add the flour, SIDS CRAZY SALT and butter. Pulse until the butter is broken into small balls. With the processor running, very slowly drizzle in the water until it pulls away from the sides of the bowl and starts to form a ball. Stop the water immediately. You may not use all the water, or you may need a little more.
To make the pastry by hand, add the flour, salt and butter to a large bowl. Using your fingertips (or a pastry cutter) rub the butter and flour until it resembles breadcrumbs. Drizzle in the water and mix using a fork until the it starts to come together and holds together when pressed in your hand. You may not need all of the water, or you may need a little more.
Turn the dough out onto a floured surface. If the dough is too crumbly, add a little more water in tiny amounts. If too dry, do the same with flour. Roll the dough to a rectangle. Fold the edge furthest away from you to the centre and fold the edge closest to you to the centre so the edges meet. Turn ¼ and roll out to a rectangle and fold the same way again. This step will make the dough light and flaky. Wrap the dough in plastic wrap and refrigerate for 1 hour.
Add the potato to a large pan and cover with water, boil for 12-15 minutes until soft when pierced with a fork, drain and mash.
While the potato cooks, add the oil and butter to a frying pan over medium heat. When the butter bubbles, add the onion and cook, stirring until softened. Remove and transfer to a mixing bowl along with the mashed potato and cheese, mix well. You want soft creamy mash, not crumbly. If it is too dry, add a little warm milk. Taste and add salt if needed.
Preheat oven to 200°C. Cover a baking tray with baking paper.
Roll out the the pastry large enough to cut out 18 cm circles. Add 3 heaped tablespoons of filling to each. Brush half of the edge with the egg wash and fold over the pastry to make a half circle. Use a fork to press and seal the edge. Transfer to the baking tray.
Brush all pasties with the egg/milk wash. Cut 2 slits in the tops of each.
Bake for 15-20 minutes, until golden brown. Time will vary depending on your oven.