Caramelised Onion

Serve as a condiment, use as a tart filling or even add to bread dough. Cook finely sliced sweet brown onions in a good quantity of olive oil in a wide, heavy-based pan over moderate heat until onion caramelises and tastes sweet. Strain, reserving the flavoured oil for other cooking. Keeps, refrigerated in a sealed container, for up to 2 weeks.