Heat oil in a large pan over high heat and add mustard seeds; fry until they begin to pop, about 1 minute. Reduce heat to medium and add carrots, celery, onion, garlic, and ginger. Cook until vegetables begin to soften, about 5 minutes. Stir in lentils, coriander, salt, turmeric, cumin, cayenne, cinnamon, and cloves. Pour in water and tomatoes. Bring to a boil, reduce heat, and cover. Simmer until lentils are soft, 15 to 20 minutes.
In the meantime, mix yogurt, cucumber, mint, and garam masala together for the raita.
Add lime juice and cilantro to the lentils. Serve with the raita.