Fresh cherries can help reduce inflammation. Turmeric is also known to reduce inflammation. Watermelon may reduce some swelling, olive oil in small amounts may be soothing, onions have quercetin in them and may reduce inflammation. Rosemary, fruits, vegetables, broccoli, cauliflower, brussel sprouts, green leafy vegetables, and kale may also reduce inflammation.
Personally I would avoid sugar since it is known to increase inflammation. In an agar plate they put sugar in it to help the germs grow on the culture deliberately so they have enough of them to test. The germs use it as a food and secrete acids that produce a sort of chemical burn like reaction in my opinion. More germs means a sorer throat in my opinion.