To prep for the caramelization process, start by slicing your onions into thin, even pieces. More even slices will make for more even caramelization overall.

Add a tablespoon of oil or butter per pound of onion to a skillet over medium heat until it has become hot, but not smoking.

Add your onions to the oil or butter, coating all of the pieces in the fat and spreading them out evenly over the entire pan to begin the ‘sweating’ process, which will take anywhere from 10-30 minutes depending on the quantity you’re cooking.

Stir the onions occasionally, increasing the frequency of your stirring once the onions have begun to brown.

Despite the textural change that you’ll see in your onions as a result of the sweating period, the actual pyrolysis reaction that causes caramelization doesn’t occur until the internal temperature of the onions has reached 100°C.

So, if you become impatient and remove the onions from the pot as soon as they get soft, your onions will lack the deep flavor and color that results from pyrolysis.

At this point, it’s imperative to keep a close eye on your vegetables to make sure they don’t burn, stirring them every few minutes to prevent sticking to the pan or charring.

If your onions appear to be sticking to the pan, add a couple of tablespoons of water, wine, or stock to the vegetables.

Once your onions begin to caramelize, you can optionally turn the heat down slightly to prevent possible burning.

You also have the option to add in a pinch of sugar or even a tablespoon or two of balsamic vinegar, which allows them to develop an even sweeter, more caramelized flavor.

Overall, the process should take between 30-60 minutes to unleash the full depth of flavor from the onions.

You can then use the finished onions in many recipes, not just French onion soup; use them on pizzas, or serve just as a side dish, or use in pasta dishes to add a sumptuous flavor. They work perfectly well, too, in curries like the recipe list above.