8 garlic cloves, unpeeled
2 pink roscoff or red onions, each cut into 6 pieces through the root
1 tardivo radicchio (or 2 large heads of radicchio), halved through the root
18 sage leaves
6 shallots, halved lengthways
small sprig thyme, leaves removed and chopped
2 tbsp olive oil
1 tbsp red wine vinegar
50ml/2fl oz light vegetable or sunflower oil
2kg/4lb 8oz pork leg, off the bone