onion omelette with balsamic vinegar

ingredients:  (could be 2 persons)
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4 eggs
120g onion chopped
olive oil 
2 teaspoon manicardi's balsamic vinegar, type 10 or 12
pepper

chop the onion (not too fine)
soften them without browning in a pan with oil
beat the eggs with a pinch of pepper, pour into pan to make omelette.

When you can see from the edge of the omelette that the underside is
 cooked, turn over. The omelette should not be overcooked or brown,
it should remain a pale golden color.

transfer to a plate and sprinkle with balsamic vinegar.

no salt !