To make the pastry, whiz flour and salt in a food processor. Drizzle in oil and then water.
Process for about 1 minute until mixture forms a ball.
Transfer to a floured work surface and knead for 2-3 minutes until supple and smooth.
Put into a bowl, cover with a clean teatowel and refrigerate for 2 hours.
Separate silverbeet stems from the leaves.
Wash and trim stems, then chop finely.
Wash leaves, then roll them up and slice finely.
Put stems into a colander and toss with 1 tablespoon salt.
Set aside for 20 minutes.
Meanwhile, boil potatoes in lightly salted water for 15-20 minutes until tender, then drain, peel and dice.
Preheat oven to 200°C and lightly oil a 28cm pizza tray.
Quickly rinse silverbeet and squeeze it dry in a clean tea towel.
Combine silverbeet with potato, onion, parsley and cheese, then add pepper to taste.
Whisk egg with 1 tablespoon oil and add to silverbeet mixture.
Taste for salt.
On a floured surface, roll out two-thirds of the pastry to a round that will easily cover the pizza tray.
Spoon on filling, leaving a 2cm border around the pastry.
Dampen border with water.
Roll remaining pastry to a round a little smaller that the pizza tray and drape it over filling.
Seal edges, then fold extra pastry from base to over sealed edges and press together.
Pierce top here and there with a fork and drizzle with 1 tablespoon oil.
Scatter with a little salt.
Bake for 20-30 minutes until golden brown.
Allow to rest for 10 minutes before cutting.
Serve with a tomato salad or other salad.
