One of our favorite breakfasts is the kale and onion omelet. I usually keep a 1/2 pint wide-mouth mason jar filled with chopped onions. They stay fresh all week and the jar keeps the odor contained.
I place a cast iron skillet on medium heat and add a teaspoon or so of coconut oil. When it gets hot, I add in the diced onions and chopped kale (I strip the leafy part from the stem first).
Once the egg sets, I use a pointed metal spatula to run around the edge of the omelet, and then fold over half. Sometimes it breaks, especially when making a five egg omelet. This three egger folded nicely.
I recommend a lot of onions and to heat them up for a few minutes before adding the egg. The taste reminds me of egg foo young but without all of the oil. You can also use more kale than I did here, and it will taste great.