Preheat the oven to 180 C, 165 Fan, Gas 4. Twist the sausages into 7.5 cm lengths and then separate into individual sausages.
Heat 1 tbsp of the oil in a 26 cm shallow flameproof casserole dish. Add the sausages and fry until nicely browned all over. Lift on to a plate and set aside.
Add the onion, garlic and another tablespoon of oil to the casserole and fry until soft and lightly golden.
Stir in the sausages, potatoes, lemon zest and juice, bay leaves, half the chopped parsley, 1/2 tsp of salt and ten turns of the pepper grinder.
Pour over the rest of the oil and 120 ml water. Cover tightly with a lid and bake for 30-40 minutes until the potatoes are tender.
Remove the lemon zest and sprinkle with the remaining parsley before serving.