Cook dal: Rinse dal thoroughly and cook in 3 cups water with turmeric until soft (about 15–20 minutes).
Heat oil: In a pan, heat coconut oil over medium heat.
Tempering: Add mustard seeds and let them splutter. Add chopped onion and sauté until translucent.
Add spinach: Stir in chopped spinach and cook for 2–3 minutes until wilted.
Combine dal: Pour cooked dal into the pan with spinach and mix well.
Add coconut milk: Stir in coconut milk and simmer for 5 minutes on low heat. Adjust salt to taste.
Serve: Serve hot with steamed rice or roti for a wholesome meal.