11/2 cups trimmed watercress (or any salad leaf variety you like)
200g smoked salmon fillet, skin discarded
Preheat the oven to 190°C (170°C fan forced). Grease a 22cm round springform.
Use a mandolin to thinly slice the potatoes to 2mm thickness. Tightly fan the slices over the base and sides of the pan, ensuring there are no holes or gaps. Bake for 20 minutes.
Whisk the eggs, cream and lemon zest in a medium bowl. Season with salt and pepper.
Pour egg custard into the potato base and bake for 20 minutes or until centre of quiche is just set. Cover the edges of potato with foil if they are colouring too quickly. Cool for 15 minutes in pan before removing.
Meanwhile, combine sour cream and lemon juice in a small bowl. Season with salt and pepper and whisk.
Top quiche with watercress, flaked salmon and dressing.