Heat 2 tbsp of the oil in a
saucepan over low heat and cook the onion, stirring occasionally,
for 15 minutes, or until soft.
Add the vinegar and sugar and cook
for 15 minutes, or until lightly browned.
Remove from the heat, stir in the
chopped thyme and set aside to cool.
Preheat the oven to hot 220°C
(425°F/ Gas 7) and heat a lightly greased baking tray.
Cut out four 10cm rounds from the
sheet of puff pastry and spread the onion evenly over them, leaving
a 1.5cm border.
Place the pastry bases on the hot
baking tray and cook in the top half of the oven for 12-15 minutes,
or until the edges are risen and the pastry is golden.
Arrange the artichokes over the
onion, then fill the spaces in between with olives and lightly
rolled pieces of prosciutto.
Drizzle the tarts with extra
virgin olive oil and serve garnished with thyme.