Preheat oven to 200ºC. Unroll the pastry and place on a lined baking tray. Score a 1cm border around the edge of the pastry; place in the fridge.
Place the butter in a pot, add the onions, and cook, covered, over a low heat for 30–40 minutes, or until caramelised and golden. Remove from the pot and set aside; allow to cool.
Heat a frying pan, add the tomatoes and cook for 3-4 minutes. Add the balsamic and sugar, cook for a further 3–4 minutes. Set aside to cool slightly.
Spread the onions onto pastry, leaving the 1cm border around the edge.
Top the onions with the tomatoes and season well. Bake for 30 minutes.
Serve hot or cold, garnished with fresh thyme, and with a green salad.
Words and image:Fairlady magazine
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