Heat olive oil in a large pot or Dutch oven over medium-high heat. Add the onion, carrots and celery and saute until the onions are translucent, about 3 to 4 minutes.
Add the garlic, cumin, oregano, salt and pepper. Stir for 30 seconds until fragrant.
Add the crushed tomatoes, lentils, broth and bay leaf. Bring to a boil, then reduce heat to a simmer and partially cover the pot leaving a small amount open to allow steam to escape.Cook for 25 to 30 minutes until the lentils are tender. Remove the bay leaf.
Add the kale and simmer for an additional 5 minutes or until the greens are wilted. Remove from the heat and stir in the lemon juice.
Serve warm.
Notes
STORAGE: Store leftovers in the refrigerator for up to 3 days. To freeze, allow the soup to cool completely. Store in a zipped-top bag or freezer safe container for up to 3 months. Thaw and reheat in a pan on the stovetop.SUBSTITUTIONS:
Lentils: Green or brown lentils work best for this recipe. Red lentils will soften and break apart so they are not recommended.
Vegetable Broth: You can also use 8 cups of water plus 2 vegetable bouillon cubes instead, if desired.
Lemon Juice: Fresh lemon juice enhances the flavors of the soup. You can omit, if desired.