Preheat the oven to 200°C.
Blend jam ingredients, excluding caster sugar, into a smooth purée using a food processor.
Melt sugar in a saucepan over low-medium heat until it becomes a golden-brown caramel.
Stir the purée into the caramel, boil, then simmer for 4 minutes until sticky.
Sear the seasoned lamb loin in a hot oven-proof pan until coloured, then roast for 10 minutes.
Baste the lamb with 2 tablespoons of jam and rest for 5 minutes.
Dissolve sugar and salt in vinegar and 110ml water over heat.
Pour the hot liquid over the vegetables, soak for 10 minutes, and drain.
Slice the lamb and serve with vegetables, garnish, and extra jam.