Heat oil in a large saucepan and sauté onions, celery, carrots and garlic on low heat for 10 mins.
Add the bell pepper and zucchini and stir for a further minute.
Add the lentils, tomato paste and oregano and stir until mixed.
Add the passata, stock and bay leaf. Bring to a gentle simmer, cover and cook for 20 mins. Stir occasionally to prevent the lentils from sticking to the pan.
Remove the bay leaf and, using a stick blender or large blender, blend until smooth.
Stir through cooked pasta.
Passata: Passata is pureed, strained tomatoes and is usually sold in bottles. It should be 100% tomato with no additives or flavourings. Some contain salt so you may wish to check the ingredients. I believe it is known as Tomato Puree in the US. If you can't find it you can replace it with crushed or chopped canned tomatoes.
Stock / Broth: Use homemade stock for babies or a no-salt / low sodium stock/broth. If you prefer you can dilute or replace it with water but it won't be as flavoursome.
Nutritional information is a ROUGH guide only, calculated using an online nutrition calculator. (1 cup of sauce, does not include pasta)