Add the olive oil or the avocado oil to a heavy bottom soup pot or Dutch oven and turn heat on to medium high.
Add the onions, carrots and celery and cook together, stirring regularly for 5 to 10 minutes.
Then add the minced garlic and stir together for 15 - 30 seconds.
Add the uncooked brown lentils, canned diced tomatoes with juice, and stir into the mixture.
And finally add 6 cups of the vegetable broth, 2 -3 bay leaves, the thyme and salt and pepper to taste.
Bring to a boil, stir and cover.
Turn down the heat and cook for about 30 - 45 minutes, stirring regularly, until the lentils are done. When the lentils are done, remove the bay leaves, **cooking time will vary for the lentils according to how fresh the lentils are.**