Place the boiled potatoes in a bowl and mash them up with a fork. The potatoes need to be lumpy, so do not use a ricer. However, if you have leftover mashed potatoes, they can be used instead as well.
Add salt, pepper and lemon to taste. Set aside.
Bring a pot of water to boil. Place the eggs carefully in the pot and cover and simmer for exactly 6 minutes. Remove the eggs, and place them in an ice bath to cool down.
Peel the chilled eggs and place them on a paper towel and pat them dry.
Place a piece of plastic wrap on your table and then a ¼ (or 1/5th, if you want to make 5 eggs with a thinner filling) of the filling on it. Using your hands, flatten it out to a long oval shape (roughly equal to the size of the egg in height and slightly longer than the circumference of the egg in width - see picture and video in post).
Place the egg in the middle and gather the ends of the plastic wrap so that the egg is enclosed with the filling. Make sure the egg is covered evenly and smoothly with the filling. Wrap the eggs with the plastic wraps and chill them for about an hour. Repeat with all the eggs.
Crush the cornflakes into crumbs. Set aside until needed (you can use Panko crumbs instead too).
When you’re ready to serve, coat the egg with flour, then the lightly whisked egg, and finally with cornflakes crumbs. You may need to press the cornflakes into the coating for them to stick.
Heat some oil (deep enough to cover the eggs) to 180°C/350°F (or until a small piece of bread dropped into the oil browns in 10 seconds). Fry 1-2 eggs at a time, depending on the size of your pan (do not overcrowd the pan). These scotch eggs only need to be fried 1 - 2 minutes per side, just until it's crispy on the outside and warmed throughout.
Flip them over gently halfway through frying. Remove from the hot oil with a slotted spoon when they turn a dark shade of golden brown in color, and let them rest on a paper towel.
Serve warm with sweet chili sauce and a salad. Enjoy!