This is a Bengali five-spice blend consisting of equal parts cumin, fenugreek, anise, mustard, and nigella seeds (kalonji). Do not substitute with Chinese Five Spice, as the flavor profile is completely different. You can find it at Indian grocery stores.
Using ghee for the final tempering provides a richer, nuttier flavor compared to vegetable oil, but both work well.
Store leftovers in an airtight container in the refrigerator for up to 3 days. Reheat gently on the stove, adding a splash of water if the dal has thickened too much.
For extra richness, stir in a spoonful of plain yogurt or a dollop of ghee just before serving.