This is a wonderful classic combination of flavours, the tart sweetness of the onions and creamy sharpness of the goats cheese. This makes a great lunch dish for two people. I use ready made all butter puff pastry for this dish, as much as I like to make my own, it is rather time consuming. 

1 packet ready made butter puff pastry
250g chevre log cut into two
2 red onions finely sliced
20g brown sugar 
30ml balsamic vinegar
Oil for frying
Beaten egg yolk for glazing the pastry

Roll the puff pastry about 1cm thick and cut into squares
With a knife make a square outline about the size of your piece of goat cheese in the middle of the pastry, do not cut all the way through, just make a slight indent
Prick the centre with a fork to prevent it from rising 
Glaze the pastry with the beaten egg and place in the fridge until you want to cook them
Set the oven to 190c (fan) 200c (normal)

To cook the onions
Fry off the onions on a low heat in the oil until soft
Add the sugar and balsamic and cook on a medium heat until they start to brown further, you don't want them to burn, 
Test the onions for sweetness, add more sugar if needed
Once cooked place to one side and allow to cool

To assemble the tarts
Place a heaped dessertspoon of the cooled onion in the centre of the pastry and place the goat cheese on top
Cook in the oven for 20 minutes until the cheese is bubbling and the pastry is golden brown