Ingredients:

  • 5 lbs yellow onions, thinly sliced
  • 2 tbsp unsalted butter, melted
  • 1 tsp sea salt
  • 1 tbsp balsamic vinegar

Instructions:

  1. Slice the onions from root to stem into uniform ribbons about ¼ inch thick.
  2. Rub the melted butter around the interior walls of the slow cooker to prevent sticking.
  3. Toss the sliced onions and salt in a bowl with any remaining butter, then transfer them to the pot without packing them too tightly.
  4. Cover and cook on LOW for 10 hours.
  5. Open the lid and stir the onions; stir in the balsamic vinegar.
  6. Leave the lid off and cook on HIGH for an additional 30 minutes to evaporate excess moisture until a jammy, mahogany-colored consistency is reached.