Brined roast chicken with a classic waldorf salad

Method

1. Start the brining and drying of the chicken 2 days before you want to cook it. For the brine, put the coarse sea salt, garlic cloves, lemon zest and thyme sprigs into a large mortar and pound with the pestle to form a coarse, flavourful paste. 
2. Scrape the paste into a strong, resealable plastic bag or box large enough to hold the chicken. Add the sugar and 1.5 litres water, then swirl the contents around until the salt and sugar have dissolved. 
3. Untie the chicken, cut off the bony end of each drumstick and remove any giblets from the cavity. Put the chicken into the bag of brine, making sure the brine and flavourings go inside the cavity, then squeeze out as much air as you can before sealing (or seal the box). Chill in the bottom of the fridge for 24 hours. 
4. When the chicken has finished brining, remove it from the plastic bag/box. Thoroughly dry inside and out with kitchen paper, put it on a wire rack and lipped tray, then leave it uncovered in the bottom of the fridge for 24 hours to dry out the skin. 
5. When you’re ready to roast the chicken, heat the oven to 190°C/ 170°C fan/gas 5. To give it a neat compact shape, first tuck the wing tips under the body of the bird. Next, with the drumsticks facing you, use a sharp pointed knife to make a 2.5cm slit in the loose skin on each side of the cavity opening. Take the right- hand drumstick and pass its end through the hole, inside to outside, on the left hand side, then repeat on the other side with the other drumstick. 
6. Rub the chicken all over with the oil and sprinkle with the salt and pepper. Spread the thyme sprigs in the centre of the wire/roasting rack and put the bird on top. Put the rack over or inside a roasting tin and roast the chicken for 1 hour 20-30 minutes, depending on the size of the chicken.
7. About half an hour or so before the chicken is ready, make the waldorf salad. Put the walnuts in a baking tray and roast for 6 minutes until lightly golden. Remove and leave to cool. For the dressing, mix the mayonnaise, yogurt, dijon mustard and mustard powder. Season to taste with salt and pepper. 
8. Put the lemon juice and sugar into a salad bowl. Halve and core the apples and cut them lengthways into thin slices. Add them to the bowl as you prepare them and briefly toss with the lemon juice to prevent them from browning. Thinly slice the celery sticks, add them to the apples (setting aside a handful of small slices and leaves from the centre) with the dressing and most of the walnuts, then mix gently. Taste and adjust the seasoning. Scatter with the remaining celery and walnuts. 
9. Remove the chicken from the oven. The meat in the thickest part of the thigh should register 70°C on a digital probe thermometer. Lift it onto a serving platter or wooden board and serve straightaway, while the skin is still crisp, together with the waldorf salad and, if you like, a simply dressed watercress salad.