Step 1(Note: This recipe is best prepared a day in advance as it will have time to soak up any excess juices.) Preheat the oven to 160 °C/ 320 °F (fan assisted), or 180 °C/ 355 °F (conventional). Peel and slice the onion and place in a hot pan greased with ghee. Cook over a medium heat until fragrant for about 5 minutes while stirring.