Add ghee to the skillet and let melt on low medium heat. Temper the ghee with cumin seeds and hing. Let cumin crackle taking care not to burn it.
Add the chopped onions and dried whole chilli. Fry the onions until they begin changing color. Don't brown.
Make the tadka. In a small sauce pan, heat up the ghee. Add the cumin seeds and let crackle.
Next, add the chopped garlic, ginger and green chilies. Fry with onions for 30-40 seconds.
Add the tomatoes next and sprinkle the ground spices - coriander powder, red chili powder, turmeric powder and salt. Mix and let the tomatoes soften slightly. Don't cook down or dry out the tomatoes.
Pour the cooked dal into the skillet and mix well. Add ⅓ to ½ cup water if needed to adjust the consistency. Bring the dal to a gentle boil, then reduce the heat to low and let it simmer for 7-8 minutes to allow the flavors to develop.
Finish the dal with chopped cilantro, garam masala powder, and crushed kasuri methi. For an extra layer of flavor, heat a small amount of ghee or oil in a pan, add cumin seeds, and let them crackle.
Turn off the heat, stir in red chili powder, and immediately pour this second tempering over the dal.
Top the dal tadka with more fresh cilantro and fried onions (if using) before serving.