Preparation

• Heat the oil in a 12-inch skillet over medium- high heat until it immediately bubbles when an onion touches it, about 1 minute. Add the onions, sprinkle with the salt, and cook, stirring frequently, until they wilt completely and begin to stick to the bottom of the pan, 10 to 20 minutes (much of the onions’ moisture will evaporate and the pan will begin to brown; the cooking time varies with the onions’ moisture content). Reduce the heat to medium low and cook, stirring and scraping the pan with a wooden spoon every few minutes. (If the pan begins to look like it’s burning, add 2 Tbs. water, stir, and lower the heat a bit.) Cook, stirring and scraping and adding water as needed, until the onions are a uniform caramel brown, another 30 to 45 minutes. (If they haven’t begun to brown much after 20 minutes, raise the heat to medium.) Add a couple of tablespoons of water and scrape the pan well. Use right away or spread the onions on a baking sheet and let cool to room temperature. Store in the refrigerator for up to one week.

For even slices, use a radial cut

• One way to ensure the most even browning is to use a radial cut when slicing the onions. By slicing onion halves on an angle, rather than straight down, you get pieces of similar length and width that will cook at the same rate.

  
  Halve the onion and notch out the ends.