Heat the oil in a large soup pot or dutch oven.  Add the onions and cook over medium heat for 3-4 minutes.  Add the garlic and cook for 1-2 minutes then add the carrots and celery.  Stir well and cook for 5-6 more minutes and then sprinkle with thyme before adding in the tomatoes and water and bay leaf.

If you don't want  chunks of tomatoes you can use tomato sauce or you can puree a large can of diced tomatoes.  I used a quart jar of my homemade canned tomatoes but a store bought 35 oz can would work fine.  You can also use fresh tomatoes, but you should peel them first by dunking them in boiling water for 30-60 seconds till the skin is loose.  If using canned tomatoes you'll want to add a pinch or two of sugar to balance the acidity of the tomatoes.  If you want a thinner soup feel free to add more water, or for a more stew like consistency just add the 1 cup mentioned in the recipe.  Add the lentils and stir well.  As a side note you can omit the lentils and 1 cup of added water and add a small can of any kind of your favorite beans after the vegetables are tender and just heat through, add the parsley and serve.  I've tried chickpeas, great northern beans and even red kidney beans and they're all delicious.

Bring to a boil, then turn down to a simmer and cooked for about 30 minutes or till the lentils are tender.  Chop up the parsley an add it to the pot, reserving some for the top of each bowl.  Remove the soup from the heat, remove the bay leaf and stir in the parsley.  Season with salt and pepper and serve hot with fresh bread or leftover noodles mixed in(gluten-free if that is a concern) and a little bit of parsley on top.