Heat a large pan, preferably cast iron, on low to medium flame.
Add the moong dal (no need to rinse first) to the pan and gently roast until it changes to a golden color, but not brown, and emits a nutty aroma. This takes about 5-6 minutes. Stir it every so often so that the dal roasts evenly. Set the roasted moong dal aside.
Boil the roasted moong dal
In a medium saucepan, bring 5 cups of water to a boil. Add roasted moong dal, and cook over medium to low flame until it is al dente, meaning until it's cooked through but still a bit hard in the middle. Takes about 10 minutes.
Cook the spices
Meanwhile, heat the mustard oil in a medium stock pot over medium flame.
Once the oil is hot, add the 1 teaspoon cumin seeds and let it sizzle for about 30 seconds.
Next, add the green chilies and grated ginger; stir only to mix. Then add the rest of the spices: turmeric powder, red chili powder, a pinch of hing, and salt.
Once your dal is ready, pour it into the cooked spices and let simmer on medium flame for another 10 minutes.
Taste your dal. Adjust the salt to your liking.
Tempering
In a tempering pan (also known as tadka pan), or any small saucepan if you don't own one, heat 1 tablespoon of ghee over medium to low heat. Add 1/2 teaspoon of cumin seeds along with a pinch of hing.
Cook until the beautiful aroma of the cumin seeds and hing fills the room, about 30-45 seconds. Pour the tempered spices and ghee into the dal and mix well. Taste the dal again and adjust salt level accordingly.
Serve
Garnish with fresh cilantro and serve with steamed basmati rice.