In a large pot, cook onion, celery, garlic, and carrots in olive oil until soft, for about 7 minutes. Add garlic, stir. Add tomato paste, stir.
Add lentils, garlic powder, salt, pepper, tomato paste, broth, and 2 cups water. Bring to a boil, then reduce to a simmer. Cover the pot and cook until lentils are tender, about 35 minutes.