Blanching a tomato makes the skin slip off easily. To blanch any vegetable, you simply drop it in boiling water, then quickly immerse in cold water.
Carefully place the tomato into boiling water for about 30 seconds, or until the skin starts to pull away. The time can vary depending on how big or how ripe the tomato is. If your pot is big enough, add three or four tomatoes at a time.
Lift the tomato out with a sieve or slotted spoon, and set it into the bowl of ice water to stop the cooking process. Leave the tomato in the cold bath for two to five minutes.