1. Rinse the lentils and drain, repeating until water runs clear (this may take 3-5 changes of water).
2. Add the lentils, 3 cups water, and turmeric to a saucepan on the stovetop. Bring to a boil, skimming off any foam, and reduce to a simmer, stirring occasionally. Simmer for 15 minutes while you prepare the other ingredients.
3. Melt the coconut oil in a large sauté pan over medium-high heat then add the cumin seed and fennel seeds. Cook for 1 minute, then add onion and cook for 3-5 minutes, until onion is soft.
4. Add the ginger, garlic, jalapeño, garam masala, fenugreek, and tomatoes and sauté for 3 minutes.
5. Add the lentils, along with their cooking water, to the sauté pan and simmer, uncovered, until thickened, about 15 minutes. Add salt to taste and serve over rice with a squeeze of lime and a sprinkle of chopped cilantro if desired.
6. For extra flavor, make a flavored oil: Melt coconut oil over high heat, add the cumin and fennel seeds, and cook for 1 minute. Remove from the heat and drizzle over each serving.