In a medium bowl, whisk the eggs, milk, oregano, a pinch of salt, and black pepper until well combined and frothy.

Heat the olive oil in a 10-inch non-stick skillet over medium heat.

Add the fresh spinach to the skillet and sauté for 1-2 minutes until it is just wilted.

Pour the egg mixture over the spinach in the pan, tilting the skillet immediately to ensure the eggs cover the bottom evenly.

Let the eggs cook undisturbed for about 2 minutes until the edges begin to set.

Gently lift the edges of the omelette with a spatula and tilt the pan to let the uncooked egg flow underneath.

Once the eggs are mostly set but still slightly moist on top, sprinkle the feta cheese and sun-dried tomatoes over one half of the omelette.

Carefully fold the empty half over the filling side and cook for another minute to warm the cheese.

Slide the omelette onto a plate, cut in half to serve two people, and enjoy immediately.