Ingredients:

  • 2 large yellow onions (about 1 lb / 450g total), thinly sliced
  • 2 tablespoons olive oil (30ml)
  • 2 tablespoons butter (unsalted), (30g)
  • 1/4 teaspoon salt (1.5g)
  • 1/4 teaspoon granulated sugar (1.5g) (optional)
  • 1/4 cup dry white wine or broth (60 ml) (optional)
  • 1 tablespoon balsamic vinegar (15 ml) (optional)

Instructions:

  1. Peel and thinly slice the onions. Aim for even slices to ensure consistent cooking.
  2. Heat olive oil and butter in a large skillet over medium-low heat. Add the sliced onions and salt.
  3. Stir the onions frequently (every 5-10 minutes) to prevent burning. Reduce heat to low if needed. Cook for 45-60 minutes, or until the onions are a deep golden brown and very soft.
  4. Sprinkle sugar over the onions. Stir to combine and cook for another 5 minutes, allowing the sugar to caramelize slightly.
  5. Pour in the white wine or broth. Scrape up any browned bits from the bottom of the pan. Cook until the liquid is nearly evaporated.
  6. Stir in balsamic vinegar. Cook for another 2 minutes.
  7. Remove from heat and let cool slightly. Store in an airtight container in the refrigerator for up to 5 days, or freeze for longer storage.