Healthy herbs, rooibos, honeybush, decaf tea, and yerba mate.
In Guilin, we have a fruit which is drived and used specifically for sore throats. I do not know if it is available anywhere else outside of China though. It is called "Luo Hanguo". It has a hard shell and is incredibly soothing for the throat. You just break up a bit of it and brew it in hot water.
Do you often wake up in the morning with a sore throat? This could be a sign of acid reflux if it occures frequently in the morning. . I love my herbs, but I have to mix in my nursing knowledge as well.