Try this recipe for Mothers Day from Jane Green's book The Love Verb
1 pack puff pastry
2 red onions, finely sliced
1 tablespoon sugar
4–6 tomatoes, finely sliced
packet feta cheese
basil leaves, finely sliced.
1. Preheat the oven to 350°F.
2. Roll out the puff pastry and cut out circles, roughly the size of a saucer. Score a circle (lightly track it with a knife) around 1 inch in from the edge.
3. Sauté the onions in olive oil until soft and caramelized (should take around 30 minutes on a low heat).
4. Add a generous splash of balsamic vinegar and the sugar after about 15 minutes.
5. Heap the onions in the middle of each circle, with sliced tomatoes in a circle on top.
6. Place in the oven for 15 minutes.
7. Crumble feta cheese onto the tarts, drizzle finely with olive oil, sprinkle with basil leaves and serve.