Crisp-skinned Spanish mackerel with plum agrodolce

Instructions

1. For the plum agrodolce, heat the olive oil in a saucepan over medium-low heat. Add the shallot and cook gently, without colouring, until very soft. Add the remaining ingredients and 60 ml (¼ cup) water and stir to combine well. Increase the heat to medium and cook until mixture has reduced by three-quarters. Set aside to cool to room temperature.
2. Preheat the oven to 200°C.
3. Lay the fish fillets on a work surface and dust the skin sides with rice flour. Place each fillet, flesh-side down, on a sheet of baking paper large enough to cover the fillets.
4. Heat a heavy-based, oven-proof frying pan over medium-high heat and add the ghee. When the pan is hot and the ghee is translucent, place the fillets in the pan, skin-side down, leaving the paper on the flesh side. Place a fish weight (or a 1-kg weight such as a heavy saucepan) on top of the fillets and cook for 2 minutes, lifting the weight once or twice and moving the fillets gently around the pan so they don't burn. Remove the weight and transfer the pan to the oven for 4 minutes. Take the fish from the oven and remove the paper. Using a spatula, gently turn the fillets over and rest for 2 minutes.
5. Meanwhile, preheat a chargrill to high. Grill the radicchio until very light charred. Place the fish and radicchio leaves on serving plates and spoon the plum agrodolce over the radicchio and part of the mackerel. Serve immediately.