It depends entirely on the sore throat. If you have strep throat or your tonsils are inflamed, you have to aim for extremely cold things such as ice cream, pudding, milk, and vegetable juice. If you have tonsiliths causing you pain, lean heavily on beat juice and gargle salt water two to three times a day for thirty seconds at a time. Drink water after every meal and brush consistently.
Should these problems persist or your tonsils start taking over your throat, go to your nearest hospital for the proper tests and medications.
The general reason for the cold foods is because when you have a sore throat, bacteria is festering in there from infection (through coughing and ailment). The cold foods will cool down your throat and assist in killing the bacteria. If you drink hot things, you will only assist the bacteria and help it manifest. Tea, soup, and oatmeal should be used primarily for headaches and stomach ailments.
Lastly, stock up on lozenges. They will be your friend.