Sift flour into a mixing bowl. Add salt and mix to combine. Add the olive oil and the egg to the bowl and blend with a fork.

Add enough water to make the pastry a firm dough. Turn this onto a lightly floured surface and knead until smooth and elastic (about 5 min). Wrap in plastic wrap and set into the fridge to chill for 30 minutes.

Heat olive oil in a shallow pan over medium heat. Add the leek, and saute until golden (about 5 minutes). Add the chard, spinach, and oregano and fry until the chard is tender (about 10 minutes).

Transfer the contents of the skillet to a bowl and then mix in the cheese and the leftover egg from the pastry. Season with salt and pepper. Set the filling aside to cool

Roll the dough out on a lightly floured surface until it's about 2mm thick. Use a floured 6cm round pastry cutter and cut into as many rounds as possible. Gather the scraps, re-roll out, and cut again. You should end up with about 20 circles. Place 1 tsp of the filling in the center of each pastry round and brush the edges with the egg white.

Fold the dough to form a semi-circle and press the edges with the ends of a fork to seal. As you complete each pastry, transfer to a baking tray lined with parchment paper. .

Heat vegetable oil in a deep pan (at least 4cm deep) over medium-high heat until it reaches about 350°F or until the oil is hot enough for frying. Add the pasties to the oil in batches and fry until brown and crisp (about 5 minutes). Transfer with a slotted spoon to a plate lined with kitchen towels

Enjoy your homemade Barbajuan appetizers!