Lots of my colleagues cough and have terrible sore throats too!

Luo han guo is a fruit found in China.

You can buy the fruit from Chinese traditional medicine shops.

The purpose of this fruit is to clear heat from the lungs, moisten the lungs, transform phlegm, stop cough and moisten the intestine.

You smashed the fruit and boiled it.

After that you can cool it, put it in refrigerator and drink it.

It taste sweet.

You can get more details here.
http://en.wikipedia.org/wiki/Siraitia_grosvenorii

Hope that helps.