Blanching is a cooking technique that involves plunging the ingredient (usually a vegetable or fruit) into boiling water for a short time and then submerging it into an ice bath to arrest the cooking process. This technique is used when you want your vegetables cooked to a precise stage (such as squeaky haricots vests) or need to remove the skins from your tomatoes, peaches or nuts.    

Bring water to a boiling point. The ingredients should have ample room to roll around in the water.

If you are blanching solely to remove the skins, simply plunge the ingredient quickly in the water for 1 minute, scoop it out with a slotted spoon, and place it on a clean dishtowel.  

If you are blanching to cook the ingredient, salt the water sufficiently so that you can taste the salt in the water. Add the ingredient to the boiling water and cook just long enough to soften the cell walls (typically 1-3 minutes). The chlorophyll in a green vegetable will transform to a bright green, the carotene coloring in a yellow or orange vegetable will brighten. Strain the ingredient (discarding the hot water) and plunge it immediately into a bowl of ice water to halt the cooking process.