Step 1

Fry the bacon in a large pot over medium heat, stirring frequently, until the fat is rendered and the bacon is crisp, 4 to 5 minutes. Add the olive oil, onions, celery, carrots, and garlic and cook, stirring occasionally, until the onions are soft and translucent, about 5 minutes. Do not brown; reduce heat if necessary. Add the tomatoes (with their juices), broth, lentils, thyme, bay leaves, salt and pepper and bring to a boil. Cover partially, reduce the heat to low, and simmer until the lentils are tender, 45 to 50 minutes (less for common lentils). Fish out the bay leaves and discard.

Step 2

Use an immersion blender to purée the soup until the broth is slightly thickened, or to desired consistency. (Be careful not to purée too much or the soup will get too thick, and you'll lose the integrity of the lentils.) If you don't have an immersion blender, transfer about 2 cups of the soup to a blender and purée until smooth, then return the blended soup to the pot. Garnish with fresh chopped parsley if desired and serve. (Note: The soup may thicken as it sits; thin with a bit of water if necessary.)

Step 3

Freezer-Friendly Instructions: The soup can be frozen for up to 3 months. Defrost the soup in the refrigerator for 12 hours and then reheat it on the stovetop over medium heat until hot.