French onion dip with gremolata

Heat the oil and unsalted butter in a large pan over a low-medium heat. Add the thinly sliced onions, with a pinch of salt. Cook for about 10 minutes, stirring every so often, until softened and starting to colour. Turn down the heat to very low and continue to cook, stirring regularly, for about 30 minutes, until the onions are golden. Tip into a wide serving bowl and allow to cool to room temperature.

Meanwhile, in a small bowl, mix together the chives, parsley, and orange zest. Once the onions have cooled, add the soured cream and mayonnaise to them and mix; season with a little salt and white pepper. Scatter over the herb mixture and serve.