luo han guo (monk's fruit) -Siraitia grosvenorii

Siraitia grosvenorii is an herbaceous perennial vine native to southern China and Northern Thailand. The plant is best known for its fruit, commonly called luo han guo or luo han kuo (from the Chinese luóhàn guǒ, 羅漢果, 罗汉果, sometimes printed lohoguo in Hong Kong), la han qua (from Vietnamese la hán quả), arhat fruit, Buddha fruit, or monk fruit. Botanical synonyms include Momordica grosvenorii and Thladiantha grosvenorii. The fruit is one of several that have been called longevity fruit. The species was named in honor of Gilbert Grosvenor.

The plant is cultivated for its fruit, used for cooling drinks and in traditional Chinese medicine. The fruit extract is nearly 300 times sweeter than sugar and has been used as a natural low-calorie sweetener in China for nearly a millennium to treat diabetes and obesity.

Traditional uses
The plant is most prized for its sweet fruits, which are used for medicinal purposes, and as a sweetener.The fruits are generally sold in dried form, and traditionally used in herbal tea or soup. They are used for heat stroke, sore throat, chronic cough, and constipation, and are reputed to aid longevity. The fruit is also used as a natural sweetener in the treatment of diabetes and obesity. (source from wiki)

Author's Input:
When someone in the house had a cough, my mom would make a cup of luo han guo, salted plum or kumquat tea for the coughing patient.  These teas usually help calm down the cough and help soothe the throat.  It was way better than taking western cough medicines.  I like the salted plum with rock sugar tea the best.