Heat oil in a large pot over medium heat.
Add onion, garlic, and ginger and cook until softened and fragrant.
Add cumin, coriander, chili powder, and turmeric. Stir for a few seconds until fragrant.
Pour in tomatoes and vegetable stock. Bring to a boil, then reduce heat and simmer for 10 minutes.
Stir in lentils and garam masala. Simmer, covered, for 20-25 minutes.
Season with salt and pepper to taste.
Serve hot with rice or naan, and garnished with fresh cilantro.
