Rouxbe

I've been making fritattas of every sort, including my version of this wonderful Tortilla de Patatas. I've made them in cast iron, Enameled cast iron, heavy weight non-stick skillets, and heavy weight stainless steel skillets. My failures occur when I try to use a light weight (cheap) skillet or my mom's Revere Ware. Just not heavy enough to hold and distribute the heat evenly. I have more trouble with oil sticking than with animal fats, either butter or lard (or bacon grease!).
When turning I like to use an old universal lid I got years ago, with no real lip, but a couple of low ridges. It has the handle on top which aids me greatly in stability. I make sure the egg is set all around, and on the bottom. If it sticks a bit during my exploration I gently lift to the sticky location and add a few drops of oil, butter, what have you. Set it back 30 to 60 seconds, then slip the fritatta sideways so the bottom is on the bottom of the lid. If you want to re-oil your pan, go ahead. I've never needed that step. I then turn the skillet upside down over the lid, seat securely, and flip them both together. This is where the handle on my lid comes in REALLY handy. I haven't had a failure on this step yet. I then cook either covered or uncovered, or a combination of both, until set.
Its important not to let the pan cool too much during the flipping. That hot pan is what will make sure the previous top, now bottom, doesn't stick. When done slide slickly onto your plate, serve or let cool, depending on your style of fritatta.