Pure vitamin C can help. I get it in pure ascorbic acid crystalline form and mix it in water or juice. You can use quite a bit, when you are sick, because your body can absorb it and use it to fight off the infection. But if you are not used to it, best to start off with a small amount because for some people the acid in it causes diarrhea or upset stomach if you overdo it. 1/2 tsp in a glass of juice 2 - 3 times a day is a good starting place.
I love miso and ginger together, and find the combination very healing. I can buy a miso/ginger broth here, which is great. But if you can't get that where you live, try a cup of hot miso broth with some ginger grated into it.
And pure honey is good for a sore throat too. It definitely works best if you can buy honey from local hives, not commercially produced honey. The closer to your home the hives are the more likely it will work for you medicinally. Don't bother if the only honey you can get is commercial, from hives who-knows-where. It might soothe your throat for a moment but won't really be healing, and the extra glucose isn't really worth it if it's not actually going to help. (Or so it seems to me.....your results may vary).
You can also gargle with warm salt water. My mother always swore by that for sore throat. I always hated it so much I never do it, but you could give it a try.