Paleo classic Spanish omelette:
Thinly slice a scrubbed sweet potato or two.
Do the same with an onion
(mandolines are great for this)
Heat a good amount of oil in a pan (olive oil is classic, lard might be more paleo, duck or goose fat would be good as well -- clarified butter would be a nice non-paleo alternative).
Slide in alternating layers of sweet potato slices and onions, slightly salting each layer.
Let the sweet potato and onion "boil" in the oil, keeping the temperature well below the smoking point, gently flipping the layers from time to time until soft.
Drain the onion and sweet potato mixture, reserving the oil.
Gently mix 4-6 eggs, salt and pepper slightly, and slide in the onion/potato mixture. The combined mixture should be heavy on the onion/potato but by no means dry.
Put some of the reserved oil in an omelette or frying pan, heat to near the smoking point, pour in the egg/onion/potato mixture, and immediately turn down the heat. (The trick here is to create a nice layer and prevent the egg from sticking -- shaking the pan slightly will help as well).
When the bottom has set a bit, throw the thing in the broiler to set the top (for extra credit, set the bottom more, and use a plate to flip the whole thing, and slide it back into the pan).
When the top is slightly browned, take it out, cut it up, and eat (also good served cold). Best when moist in the inside.
This basic recipe could be done with other paleo tubers (kohlrabi, turnips, parsnips, carrots, etc.).