For the Chorizo Harissa Butter:
Beat the butter until soft and add in the harissa spice, chorizo sausage, parsley and thyme. Beat until well combined and refrigerate until needed.
For the Turkey:
Mix all the ingredients together in turkey bag for the buttermilk brine and add the turkey breast. Tie up the bag securely and place in the salad drawer at the bottom of the fridge for up to 2 days is best but at least 24 hours.
When ready to cook the turkey preheat the oven to 190°C (375F), Gas mark 5.
Prepare the turkey breast, remove the turkey breast from the brine and drain off any excess liquid, then pat the skin of the turkey dry with kitchen paper. Place onto a roasting tin. Using a trivet is best.
Rub the prepared flavoured butter generously over the skin, this is best using gloves. Cover the top with streaky rashers.
Place the prepared turkey breast in the oven and calculate your time, 20 minutes per 450g plus 20 minutes. The turkey breast will cook much quicker than a full turkey, so make sure to keep basting; you can cover with foil if it’s browning too quickly. When cooked cover with foil to rest and keep warm.
Skim all the fat from the cooking juices, then pour off all but three tablespoons juices from the roasting tin. Stir the flour into the pan residue and cook, stirring over a low heat until golden.
Stir in the onion and thyme and then gradually pour in the stock, stirring all time. Bring to the boil, and let bubble for 2-3 minutes until thickened and the onion has cooked through. Season to taste and then strain through a sieve and keep warm.
To serve, carve the turkey breast into slices and arrange on warmed plates with the roast potatoes and vegetables. Pour the gravy into a warmed gravy jug and hand around separately.