Melt butter in a saucepan, cook chopped onions until soft, then cool.
Portion the pork belly on a chopping board.
Fine-mince the pork belly and lamb heart into a bowl containing the pig's liver.
Mix the meats with cooked onions, mace, chives, sage, egg, seasoning, and breadcrumbs.
Shape the mixture into 12 patties and chill for 1 hour.
Preheat your oven to 200°C.
Roast red onion wedges and thyme with olive oil for 40 minutes at 200°C.
Fry the chilled faggots in dripping or oil until golden brown on both sides.
Boil the stock and wine in a saucepan and reduce the volume by one third.
Lay faggots over the roasted onions, pour over the wine reduction, and lower oven to 180°C.
Bake everything together for 40 minutes.
Serve faggots topped with onions and gravy alongside mash and vegetables.