First, prepare the dal. Sort through it to remove any stones or debris. Wash the dal in several changes of water until the water runs clear, then drain it thoroughly.
In a heavy 3-quart/liter nonstick saucepan, combine the drained dal, 1½ cups of water, and 1 tablespoon (15 ml / 0.5 fl oz) of the ghee or oil-butter mixture.
Bring to a boil over high heat, stirring occasionally.
Once boiling, reduce the heat to moderately low, cover with a tight-fitting lid, and simmer gently for about 30 minutes, or until the dal is tender and plump but still holds its shape.
Do not overcook.
Remove from the heat and drain any excess water.
While the dal cooks, heat the remaining 4 tablespoons (60 ml / 2 fl oz) of ghee or oil-butter mixture in a large frying pan over moderate to moderately high heat.
When the ghee is hot, add the cumin seeds and fry until they turn a rich brown and become fragrant. Immediately add the asafetida powder, followed by the tomato pieces, ground coriander, cayenne (or paprika), turmeric, and salt.
Cover the pan and cook for 3 minutes.
Stir in the chopped spinach or Swiss chard.
Cover again and cook for another 5 minutes, or until the greens are wilted and tender. If using other vegetables like green beans or broccoli, add them at this stage and cook until tender-crisp.
Gently fold the cooked dal into the pan with the vegetables.
Lower the heat slightly, stir in the fresh lemon juice, and cook for another minute or two until the dish is heated through and has a rich, dry texture.
Garnish with minced parsley or coriander and a final sprinkle of freshly ground nutmeg just before serving.
Don't let the cumin seeds burn in the hot ghee. They should turn a rich, toasty brown and release their aroma. This tempering step, or 'tadka', builds the foundational flavor of the dish.
