Heat the oil in a Dutch oven over medium heat. Add the onion, celery, carrots, garlic, and basil; cook, stirring occasionally, until softened, 8-10 minutes. Stir in the lentils, tomatoes, broth, salt, coriander, and cumin; bring to a boil, reduce the heat to low, cover and simmer until the lentils are tender, about 30-35 minutes. Remove from the heat and just before serving, stir in the parsley.