In a frying pan sauté the onion and garlic until soft. Transfer to a bowl.
Add spinach to the pan and heat gently until wilted.
Drain and squeeze out moisture. Chop roughly.
Combine the spinach with the onion; add lemon zest, parsley and seasoning.
In a bowl Whisk the eggs gently.
Heat a small non stick frying pan with 1 tablespoon olive oil.
Add half the eggs – using a fork push the cooked egg to the centre and tilt the pan to cover pan with wet egg.
Place the half spinach mixture on one half to the omelette. Sprinkle with half the feta.
Fold over omelette and turn out of the pan onto a warm plate
Repeat with remaining mixture.