Shaykh Sulaiman Ar-Ruhaili may Allah preserve him:

What is recommended these days without prejudice to the preventive precautions and health measures Gargle before sleeping half a cup of warm water with some salt and a bit of vinegar, and in the morning eating a mixture of a tablespoon of honey and a spoon of olive oil and half a lemon mix and drink on an empty stomach, it will work in Sha Allaah

(His official Twitter account)