Use a sharp knife to cut deep lines in the fat, parallel to the string
Flip the joint over and make cuts in the flesh and push under the garlic pieces
Rub salt into the fat and set aside until oven is fully heated (up to an hour so that the fat can dry out well)
In a dish place the onions, apples, stock and sage
Place the joint on top of the stock
Roast joint in the centre of the oven for about 30 mins, until the skin starts to crisp up, then reduce the oven temperature to 180°C , and cook for a further 2-2¼ hours.
If the fat isn't crispy enough for how you like your crackling after the cooking time, turn the oven temperature up until it’s crisped up. Don't over heat or you'll dry out your meat.
Remove from oven and remove meat from the stock onto a carving platter and let sit for 15/20 mins
Remove the stock and apple and onion and safe mix and whizz in a food processor with the flour.
Return to a pan and reheat. Add extra water if the gravy is too thick
Slice the meat and serve with fresh veggies, roasties and apple sauce