Tartoufa in Tomato Sauce

• 1 kg (2¼ lb) Jerusalem artichokes
• 1 onion, finely chopped

Wash and peel the artichokes. Fry the onion and garlic in olive oil until soft and golden. Add the artichokes and roll them in the oil by shaking the pan. Add the tomatoes and squash them into the oil. Add tomato concentrate, parsley, seasoning, and lemon juice if used. Stir well and cover with water. Simmer gently for ½ hour, or until the artichokes are tender and the sauce is rich and reduced