Grate the potato into a clean tea towel. Fold the towel around the potato to form a ball and squeeze to remove as much moisture as possible, then season.
Heat a non stick frying pan over a medium heat and a few sprays of low calorie cooking spray. Place a metal chef’s ring or metal pastry cutter inside the frying pan carefully fill with grated potato. Using the back of a spoon, gently push down to make a compact cake. Remove the ring and repeat with the remaining potato. If you use a 2 inch ring you should get 3-4 röstis
Fry the rösti for 3-4 minutes on both sides, or until golden-brown all over and tender all the way through.
Season with salt, then remove from the pan, place on the plate and top with the smoked salmon.
Fill a small saucepan half-full with water and bring to the boil. Once boiling, lower to medium heat.
Tear 2 pieces of cling film (it should be at least double the width of the ramekin) and place the sheet of cling film in a ramekin. Spray with oil, and sprinkle with a little salt and pepper and break the egg into the cling film.
Gather up the edges and twist it, making sure that you have the egg enclosed well (you can use a rubber band to secure it). Repeat with the second egg. Carefully place them in the simmering water.
Cook for 4 minutes (longer if you don't like your eggs quite so runny) until the egg whites have set. Lift the egg out of the water using a slotted spoon, carefully unwrap the eggs and lift them out of the cling film using a spoon and place them on top of the smoked salmon.