Soak the split moong dal for 20 minutes in 2 cups of water. Rinse and drain the soaked dal well. Add to a pot with 2 cups of water, turmeric, and salt. Bring to a boil, then simmer uncovered for 20–25 minutes until the dal is very soft. Lightly mash and set aside.
While the dal cooks, heat ghee or oil in a wide pan over medium heat. Add cumin seeds and let them bloom until fragrant for 1 minute. Add the diced onion and sauté until soft and translucent. Stir in the green chili and ginger garlic paste; cook for 30–60 seconds until aromatic.
Add the diced Roma tomatoes along with coriander, Kashmiri chili powder, garam masala, asafoetida, and turmeric. Cook 5–7 minutes, stirring occasionally, until the tomatoes break down and the mixture thickens slightly.
Stir in the chopped spinach and cook until fully wilted and tender.
Add the spinach tadka into the pot with the cooked dal. Mix well and simmer for 5 minutes so the flavors meld. Adjust salt and consistency with water as needed.
Finish with a squeeze of lemon juice and a dollop of ghee to make it especially rich. Garnish with cilantro and serve hot with steamed basmati rice or roti.