For the salt rub
For the pickled raisins
Place the duck legs, skin-side down, in a deep tray. Combine all the salt rub ingredients in a mortar and crush them with a pestle. Pack the rub all over the duck legs and leave to marinate in the fridge for 24 hours.
Preheat the oven to 120 degrees celsius, gas mark 1/2.
Place the duck fat in a deep roasting dish and into the oven to melt completely. It should be lukewarm.
Wash off the salt mixture from the duck and pat dry before placing them in the warm fat.
Cover with aluminium foil and roast in the oven for 90 minutes.
To check if the duck legs are ready, try twisting the thigh bones; if they come away easily, the duck legs are ready.
Remove the duck legs from the fat and allow to cool slightly, if using immediately.
Remove the thigh bones from the meat and try to ensure that the meat stays in one large piece. Trim off any meat from the top of the drumstick ends so that they look neat, then tuck in the meat and trim off any loose ends.
Heat a frying pan over a medium heat and add the duck legs, skin-side down. Once golden and crisp, turn over and warm through for a couple of minutes. Alternatively, place in a hot oven for 5 minutes.
To make the pickled raisins, bring the vinegar, sugar, mustard seeds, rosemary sprig, thyme sprig, chilli flakes, salt and water to a boil in a medium saucepan. Reduce the heat and simmer, stirring occasionally, until the sugar has dissolved, for about 3 minutes. Mix in the raisins, remove from the heat, and allow to cool for at least 1 hour.
Serve the duck legs with the pickled raisins.