Turn the oven on to Broil. Wash the green chile and put it on a baking sheet and place in the oven, close to the top of the oven (but not too close)! Putting the chile in the top 3rd of the oven should work fine.
Turn the chile every 2 minutes, or when the skin has blistered.
Continue turning the chile until all the sides have been blistered.
Take the chile off the baking sheet and allow to cool for a few minutes.
Using a knife and disposable gloves, peel the blistered skin off the chile.
Open the chile and remove the stem and seeds. Use some of the seeds in your recipe if you want a hotter flavor.
Dice the chile and add it to your recipe. If you don't need all the chile, refrigerate and use within a couple of days or put it in an ice cube tray and freeze it with water.