In a large pot over medium heat, add olive oil. Sauté the chopped onion until translucent (about 5 minutes). Add minced garlic and cook for an additional minute.

Stir in the diced carrots and cook for about 3 minutes until slightly softened.

Mix in the lentils and canned tomatoes (with juice). Stir well.

Pour in the vegetable broth until all ingredients are submerged. Stir in the harissa paste.

Bring the mixture to a boil, then reduce heat to low and cover. Simmer for about 30 minutes or until lentils are tender.

Stir in chopped kale or spinach and let wilt for about 2 minutes before serving.