Caramelized onions provide a completely different taste and smell pallet from raw onions. The penetrating smell of mercaptans (Organo sulfur compounds) has disappeared. And the proteins that carry methionine and cysteine that causes our eyes to trigger an enzymatic reaction and make us cry has also disappeared in this process. Instead, the Maillard reaction between sugars and amino acids has colored the onions dark brown and the sweetness in the onions has come out.
Use caramelized onions as a taste enhancer on salads or even on meat. Or use caramelized onions as a main ingredient for example in vegetarian onion soup in a concentrated mushroom broth.
Making caramelized onions is simple, but it will go best when using a thick bottomed skillet. Also do not let the pan out of sight as specially later in the process you need to stir often. At wilfriedscooking.com we use a cast iron skillet and a wooden spatula.
Use an oil, such as olive oil or another vegetable oil to start out with. the oil will cover the onion pieces in a thin film at the outside. Also use a sufficient number of onions, as the volume reduces a lot in the process. I usually start with a heap of 3 sizeable, cleaned and cut up onions in a skillet, yielding perhaps 2 cups of caramelized onions. This is sufficient for 4-5 bowls of onion soup.
Do not cut the onions too small in size and cut even sizes, otherwise parts will be too brown and others not even.
Remember, patience is paying off, especially at the end of the process