To make Rosti
Grate potatoes, sprinkle some salt and black pepper and let it sit for 5 minutes or so. Use your hands to squeeze as much water out from the potatoes. Mix in spring onions, some grated cheese or seasoning, whatever you prefer.
Heat a cast iron or non-stick frying pan with olive oil. When oil is sizzling hot, put in potato mixture, handful by handful if you are making small individual servings, or pour all the mixture in and flatten slightly for large Rosti. Let the bottom brown, top will turn slightly translucent before flipping it over. When the bottom side browns, slide it out of the pan, top with sour cream and enjoy.