• Preheat your oven to 220°c/200°c fan (428°f/392°f).
• Roughly chop the celery, onion & carrots (no need to peel) & place into a large roasting tin.
• Add the turkey/chicken bones to the roasting tray & add in the goose fat. Toss to coat then roast in the oven for an hour or until well roasted, stirring every 20 minutes or so.
• Transfer the roasting tray to a stove set to a medium heat & turn the oven down to 150°c/130°c fan (302°f/266°f).
• Deglaze the tray with the tomato paste & port & allow to reduce slightly.

  Pour in enough cold water to completely cover the bones & veg then crumble in the stock cubes & add in the rosemary, thyme, bay leaves & peppercorns.
• Place the tray back into the oven & leave to cook for 2½-3 hours, topping up with water every hour.
• Once cooked, pass the stock into a large saucepan through a sieve then place over a low heat & skim any fat from the top with a spoon/ladle.

Finishing

• Once skimmed, increase the heat to medium-high & bring the stock to the boil.
• In the meantime, combine the cornflour with 4 tbsp of cold water, to make a slurry.
• Once boiling, gradually whisk the cornflour into the stock until it is thick enough to coat the back of a spoon (you might not need all of the cornflour).
• Cook out over a medium heat for 3-4 minutes, stirring regularly then whisk in the butter, cranberry sauce & balsamic vinegar. If you'd like to give your gravy a dark, richer colour, whisk in a small amount of gravy browning as well.
• Season the gravy with sea salt & freshly cracked black pepper then pass into a jug, through a sieve.
• Serve immediately or leave to cool then store in the fridge. Kept, refrigerated, this will last for a couple of days.

To Reheat

• Place the chilled gravy (it will have solidified) into a saucepan & add in a splash of hot water.
• Warm up over a medium heat, whisking to remove any lumps then serve once piping hot. If the gravy is a little thick, add in some more hot water.