Goal: To use only the juice of the onion to get raw onion flavor without any visible onion pieces.

I have a friend who hates eating different textures in a dish. For example, she has no problems eating peas, corn, and rice separately, but she refuses to eat them when they are combined together. So here's a tip for those who want to cut down the amount of visible ingredients in a dish, or those who don't like the texture of onions, or those who don't always feel up to the task of cutting some up but realize the necessity of onions in some cooking.
Tip:
1. Cut the onion in half and zest the insides over a bowl. Zesting, normally associated with the rinds of citrus fruits, produces minute shavings. In order to zest, use the smallest holes on your average metal cheese grater and rub them against the faces of your halved onions. Zest until you have the 'desired amount'; In order to find the notoriously elusive 'desired amount,' experiment and experiment again. I usually zest for about five to ten seconds for a smaller dish, i.e. a garlic and butter sauce. The onion is still good, but you may want to slice off the zested portion.
2. Ta-da! Finished result = Onion Juice, ready to be used to flavor your dish.