Preheat Oven to 190C

Peel and par cook the potatoes till they are only just soft inside. Put aside to cool.

Cut the sheet of puff pastry into half across the shortest length and place on a cold baking tray lined with baking paper. Refreeze the remaining pastry for later.

With a sharp knife score a line 1cm inside the pastry edge, making sure you do not cut through the pastry. Prick the base of the pastry several times with a knife or fork. Place tray with the pastry into the refrigerator to completely chill.

In a blender or using a whisk, mix the ricotta, lemon zest and miso.

Remove pastry from the refrigerator and brush the scored edges with a little egg wash (1 egg yolk with a splash of water whisked together).

Spread the cheese mix over the pastry making sure it remains inside the scored line.

Using a mandolin, slice the potatoes thinly. Layer them in alternating rows, white potato then sweet potato then white potato etc and make sure you overlap so only a small portion of each slices shows. Arrange slices until the cheese mix is completely covered.

Brush the potato with the melted butter using a pastry brush.

Sprinkle with sea salt and pepper.

Finely slice the spring onion and sprinkle on top of the potatoes

Place in the oven and cook until the potatoes are completely cooked through and the puff pastry is golden brown, approx 35 minutes.

If the pastry is going too brown and the bottom of the tart isn’t yet done, you can cover the tart with alfoil and keep cooking.

Remove the atrt from the oven and allow to cool slightly. Transfer to serving board and sprinkle with fresh picked thyme leaves and roughly chopped curly parsley.