I never said that I cook it with a lid on. I’m not that dim. I followed the Swiss YouTube clips where the chefs/housewives put a lid/plate over the rosti to flip it and return it to the pan. Sorry if I wasn’t clear.
Most recipes use soft cooking (mehligkochend) and maybe add a percentage of "festkochend" potatoes. This works best for a traditional röstli --> I agree with cannut, bintje is very good.
I like my rösti stirred, so I stir it every 5 min or so to get a nice brown color all around each piece of potato. That doesn't work with the soft cooking potatoes since it would result in mashed potatoes.
They keep very well in the pantry, I always have a few in case I'm coming home late from a weekend trip and don't have any groceries.
OP, I had the exact same problem as you until I started buying the Coop Bio rosti ... they instruct you to sauté the potato / move it around in the pan for at least 3 minutes before forming it into the pancake shape. That method works for all of the packaged ones and I've never had one stick since.
Let it burn a bit, as others said, if from the package it probably takes 2x as long as the package says. depending on your pan material and stove (gas or electric/convection)
I use a heavy German made (24 cm) pan for the potatoes - salt, pepper, lots of butter - 17-18 minutes from start if your not already hot on the stove.
Also use a separate thin pan to do the sunny side up eggs super thin, than splash em right on top of the potatoes.
Why a packet??? Par-boil some potatoes so they are 3/4 cooked, and still firm. Don't bother to peel them but grate them with a rotary grater, this will remove most of the skin. In my case add onion and some bacon bits and heat gently in a pan with plenty of butter and a touch of olive oil.
Gently move the pan so the Rosti slides about while it cooks until it forms a crust, then flip and do the same again. Flip again and leave so it becomes a beautiful gold brown nice and crunchy. Final flip to do the same again and then you'll have the best Rosti ever.
Back to the packet... get a very good non stick.. you don't need to add butter or oil get it hot put in the potato break it up then pat it down with a spatula cover the top surface tightly with tin foil and put some weight (plate) on top that pushes the whole thing down.. this is crucial.. it traps the steam which,somehow, binds the potato turn down the heat to medium leave for 15 to 20 minutes take off weight and foil put a plate on top that covers the circumference of the potato turn over the pan if it all works out (always does for me) the rosti should detach from the pan as a single unit slide the rosti off the plate and back into the pan leave for 10 to 15 optional - make some hollows add an egg (cover with lid to cook the egg) optional - springle over grated cheese