You can speed up the caramelization process by dicing the onions instead of slicing them, per The Washington Post. When onions are diced, they cook and caramelize faster.
You may have seen tips about slicing onions pole-to-pole, rather than through the equator, to speed up caramelization, as America’s Test Kitchen suggests. That cuts the time on the stove from 45 minutes to about 20 — it’s faster, but still a bit for a simple dish. When you dice the onion, conversely, you can have beautifully browned and caramelized onions in about 10 minutes.
Dicing the onions isn’t the only trick for better caramelization, either. Cook the onions over medium-high heat, which is higher than the typical recommended temperature for this task, The Washington Post advises. Stir the onions often so they don’t burn; don’t walk away from the pan. Then add some wine, which adds sugar to the mixture without being overly sweet, suggests The Washington Post. It’s those sugars that coax the most caramel flavor and color out of the onions.