Serving: 1 3 eggs30 g butter, for frying¼ yellow onion, chopped2 handfuls mushrooms, slicedsalt and pepper Crack the eggs into a mixing bowl with a pinch of salt and pepper. Whisk the eggs with a fork until smooth and frothy. Melt the butter in a frying pan, over medium heat. Add the mushrooms and onion to the pan, stirring until tender, and then pour in the egg mixture, surrounding the veggies. Using a spatula, carefully ease around the edges of the omelet, and then fold it over in half. When it starts to turn golden brown underneath, remove the pan from the heat and slide the omelet on to a plate. Tip! Serve the omelet with a crispy, green salad with vinaigrette dressing on the side.