Even though this dish makes quite a bit of food, it stores well. You can keep it in your refrigerator in a tightly sealed glass jar for up to 2 months. Or you can freeze it for up to 4 months.

• Place a Dutch oven over low heat. Once it's warm add the olive oil and stir in the onions with the salt and bay leaf. Cover and cook for 15 minutes.

• Stir it a few times to prevent sticking. Once the onions are translucent, remove the lid. Add the sherry and stir. Let the liquid evaporate and stir every few minutes to prevent burning.

• Replace the lid and cook for 1–1½ hours. If more liquid accumulates, remove the lid and let the liquid evaporate. Once there is no liquid in the pan and the onions are a light golden color, remove the bay leaf, and the marmalade is ready to serve.