The cooling down of tea is facilitated by Convection more than evaporation or radiation. Since the tea is a hot body, it does radiate and evaporate. But when we blow over the hot tea, convection plays the major role in cooling the tea down.

When we blow, the cool air of wind will replace the hot air from the upper part of the hot tea. This cool air will go down near to the tea because of the higher density compared to hot air. This will eventually make the tea cool down faster.