1.2kg/2lb 10oz courgettes (1kg/2lb 4oz prepared weight), any large halved and seeds removed, coarsely grated
125g/4½oz fresh root ginger (100g/3½oz prepared weight), peeled and finely chopped or grated
2 unwaxed lemons, finely grated zest
100ml/3½fl oz lemon juice (2–3 lemons)
cooking oil (optional)
750g/1lb 10oz jam sugar