First, sort through the moong dal to remove any debris, then wash it in a few changes of water until the water runs clear.

Drain well.

In a heavy 3-quart/liter saucepan, combine the drained dal, water, turmeric, ground coriander, minced ginger, and a small dab of the ghee or oil.

Bring to a full boil over high heat, stirring occasionally.

Reduce the heat to low, cover with a tight-fitting lid, and simmer gently for 1 hour, or until the dal is completely soft. For a pressure cooker, combine the same in the cooker, secure the lid, and cook for 25 minutes under pressure. Allow the pressure to release naturally.

Once the dal is cooked, remove the pot from the heat. Use a wire whisk to beat the dal until it is creamy and smooth.

Stir in the salt and the chopped fresh spinach. Return the pot to the heat, cover, and simmer for another 5-8 minutes, just until the spinach has wilted.

Prepare the final seasoning (tarka).

Heat the remaining ghee or oil in a small saucepan over medium-high heat.

When the ghee is hot, add the cumin seeds and fry until they turn a rich brown color. Immediately add the asafetida and cayenne pepper, fry for just 1-2 seconds more, then quickly pour the entire mixture into the dal soup.

Cover the dal immediately to trap the aromas and let the seasonings infuse for 1-2 minutes. Just before serving, stir in the fresh lemon juice.

Serve hot.

Don't overheat the ghee or oil for the final seasoning. The cumin seeds should sizzle and turn brown, not black, to avoid a bitter taste.