Preheat the oven to 180°C (fan).
Add the potatoes, carrots, leek, onion, apple, garlic and lots of rosemary and thyme to a roasting tray. Season with extra virgin olive oil, sea salt and black pepper.
Pour over the stock and roast in the oven for 30 minutes.
Remove from the oven and toss the vegetables.
Prick the sausages with a fork and nestle them into the tray without covering with vegetables.
Drizzle again with extra virgin olive oil and season. Roast for 45 minutes, turning the sausages over halfway through.
Remove the tray from the oven and add jam and mustard. Mix thoroughly and position the sausages back on top of the vegetables.
Roast for a final 30 minutes until the sausages are piping hot and the vegetables are softened.
Serve and spoon over some of the sweet, mustardy stock from the base of the tray.
