In a large cooking pot, coat the bottom with 1 Tbsp. vegetable oil and place it over medium heat. Give the oil a minute to heat up, then add the diced 1 red onion. Sweat the onion for about 5 minutes, until it becomes soft and translucent.
While the onion is cooking, in a mixing bowl, stir the minced 4 garlic clove, 2 tsp. ginger, 2 tsp. garam masala1 tsp. cumin, 1/2 tsp. turmeric and 1/4 tsp. cayenne pepper.
Add the mix to the cooking pot once the onion is ready. Cook everything for about 1 minute, until the mixture becomes very fragrant.
Stir in the 2 cups dried split red lentils and 4 cups vegetable broth. Raise the heat and bring the mixture to a boil. Lower the heat and allow the soup to simmer, uncovered, for about 20 minutes, until the lentils are very soft.
Stir in the 400 ml coconut milk and 800 ml finely chopped tomatoes. Continue simmering for about 5 minutes, until the soup is very thick and the lentils have fallen apart. Remove the pot from the heat and stir in the 2 Tbsp. lemon juice. Season the soup with salt and freshly ground black pepper to taste.
The Serving
Ladle into bowls and top with fresh cilantro. Serve with rice or bread.