Preheat a nonstick pan over medium heat with some olive oil.
Slice the asparagus thinly and add to the pan, lay them next to each other covering the whole pan.
Let them fry for 1-2 minutes.
Meanwhile whisk the eggs in a bowl until small bubbles start to appear.
Pour the whisked eggs over the asparagus in the pan and slightly tilt the pan so the eggs cover the whole pan.
Fry for 3-4 minutes.
Add the crumbled feta cheese.
Fry until the omelette until it has desired texture.
Gently fold the omelette in half and put it on a plate.
Top with freshly ground black pepper, salt (if using) and mâche salad.