Put your grated potato and sweet corn into a bowl, sprinkle with salt and set aside for 5 minutes in order for the salt to draw some of the water from the potato
Heat a knob of butter in a large frying pan. While the butter is melting, squeeze your potato and corn mixture in your hands to get rid of the water, and place the mix on some kitchen paper
When the butter is melted, place spoonfuls of the potato mix into your pan in little mounds, pressing down with the back of the spoon to flatten them. Add more if there are any holes in your rosti and you want them to hold together. Make sure you press them down again if you add any more. Fry for about three minutes then using a spatula or palette knife, gently flip them over to cook the other side, another three or four minutes should do. Don't overcrowd the pan. Do it in batches if necessary, and keep the cooked ones under foil to keep warm. If necessary you can keep them warm in the oven.
Once the rostis are done, you can get on with your poached eggs. Bring a pan of water to the boil, and using the freshest eggs you can get, crack each one into it's own little glass or cup. When the water is simmering, turn it down low, and gently lower your eggs into the water, pouring them out of their respective cups. Gently cook them in the water, when they're ready they will lift themselves up from the bottom of the pan, this should take about two or three minutes. Fish them out of the water using a slotted spoon, and drain them on some kitchen paper.
To serve, lay a bed of rocket, and place your rostis on, then top with a poached egg, season with salt and pepper and enjoy!