Co-op plain flour, for dusting
375g pack ready rolled puff pastry
2 tbsp Co-op olive oil
100g Co-op Fairtrade light brown soft sugar
3 tbsp Co-op cider vinegar
3 tbsp Co-op ruby port
1 tsp dried thyme
Thyme leaves, to serve (optional)
Preheat the oven to 200°C/fan 180°C/Gas 6
Dust the work surface with a little flour and roll the pastry out to a circle just bigger than 28cm diameter.
Cover in greaseproof paper and chill in the fridge.
Slice each onion into 3 or 4 thick rounds. Heat the oil in an ovenproof frying pan, 28cm across, then carefully arrange the slices in 1 layer and fry for 5-7 mins over a high heat, until golden and lightly charred.
Mix the sugar and vinegar together, pour around the onions and bubble over a high heat for 5-6 mins, until reduced and syrupy. Swirl through the port and thyme, then bubble for 1 more minute.
Take off the heat and allow to cool for 5 mins. Place the chilled pastry over the onions and tuck in around the edges.
Put the pan directly into the oven and cook for 25-30 mins, or until puffed up and golden brown.
Once it’s cooked, turn the tart out onto a serving platter and cut into wedges.
Serve garnished with a few thyme leaves, if you like.