We love this recipe. We eat it as a starter if we have friends over and also as a main meal with salad. It is so simple and yet so tasty even our Spanish friends like it! This recipe also came from my amazing veggie book (Hugh Fearnley) but again I have played around with the recipe to suit us as I am sure you will.

Rough puff pastry (see making pastry for the recipe)
4 large onions
Olive oil
Balsamic vinegar.

Preheat your over to 200 degrees
Peel the onions, cut in half and then slice along the short length.
Pour enough olive oil to cover the bottom of the frying pan. This pan should be oven proof too)
Cook the onions slowly until they start to caramelize.
Add balsamic vinegar to your taste and stir into the onions
Take the pastry from the fridge and roll out to the size of the pan
Place the pastry on top on the onions and place in the oven until brown.
This can take 20 to 30 minutes.
Take out of the oven. Place a plate on top of the pan and turn it over so that the pastry is on the plate. Scrape out any onions that have stuck to the pan.
Serve hot.