To make the stuffing, soften the chopped onion in half the butter.
Melt in the rest of the butter, stir in the breadcrumbs and herbs and season.
Preheat the oven to 220°C / 425°F / Gas mark 7.
Remove the string from the pork.
The skin will be scored, but add a few more slashes with a knife or very sharp kitchen knife.
Turn the pork over. If you are using leg, make a deep cut along the joint.
Open it out, then press in the stuffing.
Re-tie the pork.
For loin, push the stuffing into the cavity.
Rub the joint with oil, then 1 tablespoon of salt, pushing into the skin.
Sit the pork on the sliced onion in a shallow roasting tin.
Roast for 25 minutes or until the skin has started to crisp and turn golden, then reduce the heat down to 190°C / 375°F / Gas mark 5 and cook for 1 hour 15 minutes (or 50 minutes per kg)
Half an hour before the end of cooking, cut the apples into chunky quarters, then toss in a baking dish with a squeeze of lemon juice.
Add the red onion to the dish with the oil, butter, some salt and pepper.
Roast on the shelf below the pork for 20 minutes or until tender.
Add in the sugar, herbs and another squeeze of lemon and roast for 5-10 more minutes, or until sticky.
When cooked, transfer the pork to a serving board or platter uncovered.
Spoon out the excess fat from the roasting tin, then set the tin over a gentle heat.
Whisk in the flour and cook for 1 minute, then slowly whisk in the cider until smooth, scraping in all the cooking bits.
Add the stock then simmer for 10 minutes, then season to taste.
Spoon the sticky apples and onions around the pork, scatter with herbs if you like.