Start by washing and chopping your vegetables. Dice the portobello mushrooms and onions finely, and remove the stems from the kale before chopping it into smaller pieces.
In a non-stick frying pan, heat the olive oil over medium heat. Once hot, add the chopped onions and mushrooms. Sauté for about 3-4 minutes until they begin to soften. Next, add the kale and cook for an additional 2 minutes, until it wilts down. Season with a pinch of salt and pepper.
In a mixing bowl, crack the 3 large eggs and whisk them vigorously until well combined. You want them to be light and fluffy, so take your time with this step!
Once your vegetables are ready, push them to one side of the pan. Add the butter to the other side of the pan and let it melt. Once melted, pour the whisked eggs into the pan, tilting it to spread them evenly. Let it cook for about 2-3 minutes, or until the edges start to set.
Before the eggs are fully set, sprinkle the mozzarella cheese evenly over the top. Allow it to melt slightly as the eggs continue to cook.
When the eggs are mostly set but still slightly runny in the center, use your spatula to gently fold the omelette in half. Cook for another minute, allowing the inside to firm up and the cheese to melt completely.
Slide the omelette onto a plate and serve immediately. You can garnish it with fresh herbs or extra cheese if desired. Enjoy your delicious creation!
