Method

• 1.
  For the pastry, combine the flour and 1 tsp salt flakes in a food processor. With the motor running, add the butter, 1 piece at a time, and process until well combined. Add the egg and sour cream, and pulse until it just forms a ball.

• 2.
  Turn the pastry out onto a lightly floured surface. Roll out until 3mm thick. Transfer to a deep 30cm loose-based tart tin and trim any excess pastry. Chill for 20 minutes.
• 3.
  Preheat the oven to 200°C.
• 4.
  To make the filling, cook the speck in a large frypan over medium heat, stirring often, until the fat starts to render. Add the butter, onion and silverbeet stems, and gently cook, stirring occasionally, for 12 minutes or until soft. Add the silverbeet leaves. Cook, stirring occasionally, for 5 minutes or until wilted. Transfer to a colander to cool and drain.
• 5.
  Place the tart tin on a baking tray and prick the pastry base all over with a fork. Line the pastry with baking paper and fill with baking weights or dried beans. Bake the tart for 20 minutes, then remove the weights and paper, and bake for a further 10 minutes or until the pastry base looks dry.
• 6.
  Whisk the eggs, sour cream and cheeses in a bowl. Fold in the cooled silverbeet mixture. Generously season with salt flakes, ground white pepper and sweet paprika.
• 7.
  Reduce the oven to 180°C.
• 8.
  Spoon the filling into the pastry case. Bake for 40 minutes or until the pastry is crisp and cooked through and the filling is just set. Cool the tart in the tin a little before slicing, then serve topped with rocket, dressed with lemon juice and oil.