Heat a generous drizzle of extra virgin olive oil in a large Dutch oven over medium heat. Once shimmering, add the diced onion, carrots, and celery, stirring frequently. Cook for about 4-5 minutes until the onion softens and becomes translucent.

Stir in the tomato paste, minced garlic, ground cumin, dried oregano, dried basil, dried thyme, kosher salt, and black pepper. Sauté this mixture for 1-2 minutes, allowing the spices to bloom.

Add the fire-roasted diced tomatoes, low-sodium vegetable broth, and rinsed green or brown lentils to the pot. Bring to a rolling boil, then lower the heat to a gentle simmer. Cover partially and let it cook for 25-30 minutes.

If a creamier texture is desired, use an immersion blender to blend part of the soup directly in the pot, or transfer some to a regular blender, then return it to the pot.

Stir in the sliced kale leaves and a generous squeeze of fresh lemon juice right before serving. Allow the soup to simmer for an additional 1-2 minutes until the kale wilts.