I've only used this one once, and I definitely found it to be nasty, so you've been warned. But I swear it worked for me when I was downright miserable with what I think was the worst sore throat I've ever had.
Add 1/2 teaspoon of cayenne pepper to 1 cup very hot water, stir well and gargle. Repeat every 15 to 30 minutes as needed.
I found an explanation of why it might work on a naturopathic site:
This brings more circulation to the area and helps draw away the infection.
But personally I think it might just be because after enough cayenne pepper, you can't feel anything anyway... but when you're desperate, who cares.
Good Luck, I hope you find something that works for you. Feel Better!