Heat the olive oil in a large pot over medium heat. Add the onion, garlic, and ginger and cook until the onions are translucent, about 5 minutes.
Add the cumin, coriander, garam masala, turmeric, cardamom, cinnamon, cayenne pepper, black pepper, nutmeg, cloves, and mace and cook until fragrant, about 1 minute.
Add the vegetable broth, lentils, tomatoes, and coconut milk and bring to a boil. Reduce heat to low and simmer until the lentils are tender, about 20 minutes.
Add the lemon juice and season with salt and pepper, to taste.
Serve hot.
Interesting Facts
Mulligatawny is an Indian-inspired soup made with a variety of spices.
It is traditionally made with chicken or lamb, but can be made vegan or vegetarian.
The name Mulligatawny comes from the Tamil words for "pepper water".