Sorrelishious! ok, not a word...

Its sour taste comes from oxalic acid, which also gives rhubarb its tartness. ... Personally, I like sorrel's tangy taste in salads.

Sorrel is a small edible green plant from the Polygonaceae family, which also includes buckwheat and rhubarb. The French translation of sour (“sorrel”) is spot-on: These leaves have an intense lemony tang. In Vietnamese cuisine, sorrel leaves are known as rau thom (fresh herb), and it's called gowkemeat in Scotland. 

Uses:   Sorrel is used for reducing sudden and ongoing pain and swelling (inflammation) of the nasal passages and respiratory tract, for treating bacterial infections along with conventional medicines, and for increasing urine flow (as a diuretic).