Heat the coconut oil in a large pot or skillet over medium-high heat. Add the cumin and coriander seeds and toast until they start to brown, about 45 seconds. Add the garlic to the pot and let it brown, about 2 minutes.
Add the can of crushed tomatoes, ginger, turmeric, and sea salt to the pot and cook, stirring the pot a few times, for 5 minutes.
Add the lentils and, if using, the cayenne powder and 4 cups of water to the pot and bring it to a boil.
Reduce the heat to low, cover the pot, and let it simmer for 35-40 minutes, or until the lentils are soft. Stir the pot a few times to prevent the lentils from sticking to the bottom.
Once the lentils are soft, add the coconut milk and cherry tomatoes and bring the pot back to a simmer. Remove the pot from the heat and stir through the cilantro.