To caramelize onions, start by thinly slicing the onions evenly. Heat a combination of butter and oil (such as olive oil or avocado oil) in a skillet over medium heat, then add the onions with a pinch of salt. Stir the onions initially for a few minutes until they soften, then reduce the heat to medium- low or low and continue cooking, stirring every few minutes or so. If the onions begin to stick or dry, add a splash of water or broth to deglaze the pan and prevent burning. This slow cooking process takes about 45 minutes to an hour or more, depending on the desired level of caramelization. The onions should turn deeply golden brown, soft, and jammy when done. This method brings out the natural sugars in the onions, producing a sweet, rich flavor that enhances many dishes such as burgers, soups, dips, pasta, and more.