Seville oranges are sold in the last three weeks of January. Bitter (Seville) oranges are classically used in cooking, not just in marmalade but also in dishes such as Duck à l’orange.

Now is the perfect time to take advantage of in-season citrus fruits and use them in salads and cooking. Blood orange and fennel is a popular Sicilian salad often enhanced with black oil cured olives.

It can easily be made gluten-free too. Wash the oranges thoroughly. Bring them to the boil in a large saucepan of water and gently cook for two hours. Preheat the oven to 175C/325F/Gas 3 and ...