Put the lentils in a saucepan with the bay leaf, cover with cold water and bring to the boil. Reduce the heat and simmer, covered, for 15 to 20 minutes or until the lentils are tender. Drain the lentils and set aside.
Meanwhile, heat the olive oil in non-stick saucepan over very low heat. Add garlic and onion, cover pan and cook for 7 to 10 minutes or until softened. Bring a large pot of water to the boil (for cooking the noodles).
Add the drained lentils, carrot, celery, mustard and sherry to the onion-garlic mixture in the pan. Season with pepper to taste and mix well. Raise the heat to medium, cover the pan and cook for 2 to 3 minutes.
Add the spinach and 3 tablespoons hot water (you can use the noodle cooking water), cover the pan again and continue cooking for another minute or until vegetables are tender, adding more hot water if the mixture seems too dry. Adjust the seasoning to taste.
Cook the noodles in the boiling water according to the packet instructions, about 4–6 minutes or until al dente. Drain the noodles, reserving a little cooking water. Toss the lentil mixture and parsley with the noodles, adding enough water to moisten if necessary. Season to taste.