As a culinary herb, it is used mainly in salads. The flavour of French sorrel is slightly bitter or tangy, spiced with a hint of lemon; the sharp flavour is due to oxalic acid.French sorrel is hardy in most regions, tolerating frost, full sun and short dry spells.It grows quickly to a clump up to 1 metre (3.3 ft) in diameter, with long leaves up to 10 centimetres (4 in) in width. It is sometimes preferred for culinary uses to Rumex acetosa, garden sorrel.