To make the gravy, preheat the oven to 220C/200C Fan/Gas 7. Put the chicken wings in a large roasting tray and roast for 30 minutes, or until golden brown.
Transfer the chicken to a plate and set aside. Add the vegetables and garlic to the roasting tray and toss in the chicken fat. Roast for 40 minutes, or until golden and caramelised. Put the tray over a high heat and add the tomato purée. Deglaze the pan with the wine, add the Parmesan rind and allow to bubble. Return the chicken wings to the tray and pour in both stocks. Bring to a simmer and cook until reduced.
Meanwhile, for the chicken thighs, put 1 litre/1¾ pints water in a large pan and add the salt. Bring to the boil then remove from the heat. Add the herbs and lemon and allow to cool. Once fridge cold, put the chicken thighs in the brine and leave in the fridge for 1 hour.
Remove the chicken thighs from the brine and rinse, then put them in a sous vide bag. Cook them in water bath at 62C for 4 hours.
Strain the gravy from the chicken wings into a clean pan and place over a medium heat. Discard the wings and vegetables. Bring to a simmer and reduce until you have a thick, pourable gravy. Remove from the heat and add the kombu, sage, thyme and lemon zest and leave to infuse.
Meanwhile, to make the swede purée, put the swede in a pan with the butter. Season with salt and pepper and put on the lid. Place over a medium heat and allow the swede to steam for 30–40 minutes until soft. Transfer into a food processor and blend until smooth.
Remove the chicken thighs from the water bath and allow to rest for 20 minutes. Remove the chicken from the bag and put into a frying pan over a medium heat. Cook until the skin is crispy.
To serve, spoon some swede purée onto four serving plates, top with a chicken thigh and pour over the gravy.