Method
Place the raisins in a small bowl and pour over the orange juice. Leave the raisins to plump up for 30 minutes or so.
Place the cabbage on a board and, using your sharpest knife, thinly slice into long, delicate ribbons. Use a mandoline or the same sharp knife to cut the celeriac into super-thin matchsticks.
Place the raw vegetables in a large bowl with the orange-soaked raisins, the thyme leaves and the olive oil. Season with salt and pepper and use your hands to tumble everything together. Set aside while you cook the partridges.
Heat the oven to 200°C/400°F/gas mark 6. Place the partridges, breast-side up, in a small roasting tray and spread them all over with the butter, then season with salt and pepper. Place the roasting tray in the oven and cook the birds for 25–30 minutes, until the skin is golden brown. Remove from the oven and flip the birds over onto their breasts to rest for 10–15 minutes in a warm place.
Place the birds on a board. One bird at a time, use a large, heavy knife to cut the partridges in half: place the knife on one side of the breast bone and cut down all the way through to the board. Repeat on the other side of the breastbone so that you’re left with a central piece of the bird, which you can discard. Repeat the process for the other partridge.
Divide the partridge halves equally between two plates next to a serving of the salad. Trickle over some of the orangey salad dressing and spoon over any partridge roasting juices. Take to the table straight away.