Stuck (Literally)

I've always heard that cast iron, when properly seasoned, is supposed to be nearly non-stick, requiring little in the way of fats when preparing food. If that's the case, then I'm doing something horribly, horribly wrong.

I have three cast iron skillets, and every time I make my potato rosti (what we here call "potato flip"), it sticks no matter which pan I use. I've thought that perhaps my pans weren't well seasoned, so I used my favorite search engine and found several sites with seasoning instructions. One site even recommended blasting off all the accumulated crud by running the cast iron through the self-cleaning cycle of the oven, which I tried over the weekend and then reseasoned. No luck. My potato rosti stuck again this morning. Maybe it's just that potatoes are somewhat sticky when raw (I use russets)? I'm using fats when I cook, so it's not like the pan is dry. Perhaps my pan is too hot? Is that even a possibility with cast iron? Anyone out there in the Interwebnetland have any suggestions?