Sorrel (Rumex acetosa) is known for its fresh, sour flavour. The oxalic acid contained in the leaves is responsible for its flavour. In the Middle Ages, sorrel was used to help prevent scurvy.
Sorrel can be prepared in the same way as spinach, or the two can be mixed together to give a slightly more seasoned flavour. It also tastes great raw when added to salad. Sorrel is one of the seven herbs used in Frankfurt green sauce.
Large amounts of sorrel should not be eaten raw, as the oxalic acid can cause an upset stomach. Almost all the acid is broken down when cooked, meaning that it can be safely consumed, even in large quantities.
Sorrel should be stored at fridge temperature.