Place a clean tea towel (or an unused J cloth) in a bowl and add grated potatoes, layering with 5 pinches of salt
Set aside for 10-15 minutes
Meanwhile, crumble the feta with your fingers or a fork and mix in creme fraiche until smooth
Slice the chilli into thin strips, 2cm long
Do the same with the preserved lemon, only using the skin.
Gather up the corners of the tea towel, twist and wring out the juice of the sweet potato. Keep doing this until the potato is quite dry. Tip into a clean bowl and add some freshly ground pepper and a beaten egg.
Heat a non stick frying pan, add 1 tbsp of sunflower oil.
Shape little patties in your hand and add to the pan.
After a couple of minutes and when the rosti is turning a golden brown, turn them over.
Lift out the rosti and place on kitchen roll to absorb any excess oil, top with a little feta mix, a slice of preserved lemon, chilli and a coriander leaf.