Preheat your skillet over medium heat. (Use a non-stick or low-stick pan like a well-seasoned cast iron or properly preheated stainless steel.)Once the pan is hot, add the butter followed by the onions. Cover and cook for 5-7 minutes, stirring occasionally until softened.
1 tablespoon butter
While the onions cook, crack the eggs into a bowl, add the salt and whisk (a fork works) until well combined.
3 large eggs, ⅛ teaspoon fine sea salt
Reduce the heat to medium low and pour in the eggs evenly over the onions. Cover the skillet with a lid (to help cook the top without flipping).
After about 2 minutes, spread the cheese over one half of the omelet. Cover again and cook for another 2-3 minutes until the eggs are just set and the cheese is melted.
Add the diced avocado over the cheese, fold the omelet closed and transfer to a plate. Enjoy!
Notes
Leftovers: This omelet is best enjoyed fresh, but if you do have leftovers, store in the refrigerator for up to two days. Reheat in the microwave or gently in a skillet. Ideally, store the avocado separately and add it after reheating.Make Ahead: For easier mornings, you can prep the sautéed onions ahead of time and store them in an airtight container (up to 3 days ahead).
Nutrition Note: Nutritional information is estimated using an online calculator and accuracy is not guaranteed. Remember food is more than numbers and this info is intended as a support.