Makes about 1 ½ cups
2 ½ lb sweet onions such as Vidalia or Walla-Walla (about 4 medium)
2 Tbsp extra-virgin olive oil
Tip 1: Start with sweet onions. Although all varieties of onions work, starting with sweet onions eliminates the need to add sugar, as some other recipes suggest. Remember that onions are naturally sweet. When cooked for long periods with controlled heat, the sugars break down and transform into smaller sugar molecules, resulting in deep browning and concentrated sweetness.
Tip 2: Slice the onions lengthwise. This helps them hold their shape without falling apart during the long caramelization process. Radial cuts are best because they deliver more uniform slices. Simply cut following the natural curve of the onion and its lengthwise ridges that run from top to root.
Tip 3: Salt the onions at the start of cooking. This will draw out their moisture immediately. Consequently, they might take a little longer to start caramelizing, but the result is more even browning and a rounded flavor.
Tip 4: Get a big pan. It’s absolutely essential to use a large skillet for this, a 12-inch cast iron pan is ideal. The pan might seem overcrowded when you’ve added all the onions, but they’ll slowly begin to shrink down as their moisture cooks off. Adding water in small amounts when the onions start to stick to the pan will loosen the fond (the flavor-packed browned bits that stick to the bottom of the pan) and prevent burning.
Tip 5: Most importantly, be patient and don’t raise the heat. Some recipes advise that a pinch of baking soda will speed up the browning process; this is true, but don’t do it! The baking soda will turn your beautiful onion slices to mush. Caramelizing onions takes time, but it’s so worth it! As a reward for your patience, you get 1 ½ cups of silky sweet, caramelized bliss.
Caramelized onions are made by very slowly cooking onions until they’re meltingly soft, deeply browned, and wonderfully sweet. Preparing caramelized onions is a technique you’ll learn once and master forever; it’s that easy. What follows is a basic caramelized onion recipe, plus the five tips you need to make a perfect batch of this sweet and savory treat.
Peel, trim, halve the onions lengthwise, and cut into ¼-inch thick slices.
Heat the oil in a large skillet on medium-high heat until just warmed through, about 45 seconds. Add the onions and 1 tsp salt. Cook, stirring frequently with a wooden spoon, until the onions begin to wilt, brown in places, and stick to the pan, 15 to 20 minutes.
Reduce the heat to medium-low, and continue to cook, stirring and scraping the pan occasionally. If the onions begin to look or smell like they're burning, add 1 or 2 Tbsp of water, lower the heat, and continue to cook, stirring and scraping up any brown bits in the pan. Continue stirring and scraping the pan, adding water, and adjusting the heat as needed until the onions are a rich dark brown, caramelized, significantly reduced, and silky another 35 to 45 minutes.
Enjoy the onions immediately, or cool and refrigerate in an airtight container for up to one week.