Pour the lentils on a cookie sheet and pick them over, removing any pebbles or debris. Pour the lentils into a strainer and rinse thoroughly. Set aside while you chop the vegetables.
Heat the oil in a large stock pot over medium heat. Add the onions, carrots, celery, garlic, salt, pepper, oregano and basil. Stir to combine and let the vegetable sweat (to release moisture) for about 10 minutes, or until the onions begin to soften. If they start turning brown, back off on the heat.
Add the cumin, bay leaves, lentils and water. Stir well and turn up the heat. When the soup comes to a boil, turn it down to very low heat, cover and let simmer for 35 minutes.
Remove the bay leaves. Either use an immersion blender to lightly puree the soup, or scoop out a few cups and puree in a food processor or blender and return to the pot. Keep pureeing until you reach a desired consistency.
Add more salt and pepper to taste per bowl. The flavors meld very well overnight, so don't over-salt the pot.