A vaporizer or humidifier
A sore throat comes from many different reasons. Your throat is irritated by the inflammatory effects of a viral infection. However, another important reason is the dryness of your pharyngeal mucosa. If you wonder why you wake up with the worst symptoms and they tend to relieve a bit as the day goes by, one of the reasons is that breathing through the mouth dries your mucosa, and low circulation of saliva promotes bacterial growth.
Thus, an air humidifier is a fitting way to fix that, especially if you have nasal congestion and feel forced to do mouth breathing. You can also use a vaporizer or simply boil water and breathe the steam. However, as you do it, be careful not to burn yourself from the hot steam. A good idea would be to stay close to the boiling water and wave the steam towards your face.