Remember playing with play dough as a child; the device that was used to make hair and play dough spaghetti? This device is similar to the garlic torture device that plagues kitchens today. Garlic should never be placed in one of these devices. Garlic should never be smashed with the back of a knife. These techniques expose the alkaloid sulfur compounds to air which allow it to be easily oxidized. This turns the garlic bitter. Discerning palates do not like oxidized garlic.
Here is a technique which is quick easy and allows more garlic to be used in a dish without the bitter oxidized bitter flavor.
First cut root end off of the clove.
Take paring knife and split garlic in two halves. If bitter green sprout is present remove it with tip of knife.
Cut skin comes off easily.
Peeled garlic is easy to do. It can now either chopped or used as is. I like to use whole split pieces of garlic, it cooks sweet and does not produce a bitter overpowering oxidized garlic flavor.