Heat 2 tablespoons oil in a small frying pan, about 8 to 10 inches wide, over medium-high flames.
When oil is hot, pour the egg mixture into the frying pan and cook for 1 minute, then reduce the heat to low.
Shake the frying pan from time to time and run a palette knife around the edge of the omelette so that it won't stick to the pan.
Cook until the egg has only a moderate circle of the wet mix on top about 10 minutes.
Run a fish slice or palette knife around the sides and under to make sure the omelette is not stuck to the frying pan.
Pick the frying pan by the handle, place a wide plate over the frying pan, press down and quickly flip the omelette into the plate.
Set the frying pan back onto the flame and gently slide the omelette and any liquid into the frying pan.
Raise the heat to high.
Tuck in the sides of the omelette to make it look neat and round.
After about 1 minute, reduce heat to low, shake the pan to loosen the omelette.
Cook till it is springy to touch, or when a toothpick is inserted into the middle, it comes out clean.
The residual heat will dry it out some more. If you want it runny, don't cook for too long once you flip.
Slide onto a plate, your Spanish omelette is ready.
Leave to cool a little before cutting.
Serve warm or cold with bread and a salad e.g Sweet corn salad.