Over medium-high heat, add the olive oil in a cast-iron pan or large, heavy skillet at least 12 inches in diameter. Swirl to coat the pan.

Add the sliced onions, one-third at a time, and toss in the oil until properly coated.

Sprinkle with ¼ teaspoon of salt and stir constantly for about 2-3 minutes or until they start to soften.

Lower the heat to low and cook, uncovered for about 45 minutes or until the onions become very soft, slightly sticky and a deep golden brown. Stir the onions every 3-4 minutes.

If they begin to stick to the bottom of the pan, add a tablespoon or so of water and simply scrape the bits off. Consider lowering the heat if they start to burn.

Towards the end of the process, a few minutes before the onions are done to your liking, add 1-2 tablespoons of water, stock or wine to de-glaze the pan. When the liquid evaporates, they are done.

Use immediately or cool to room temperature and refrigerate for up to three days or place in an airtight container, cover and freeze for up to one month.