Prepare the Eggplant: Trim the tops off the eggplants.
Cut them into 1-inch by ¾-inch dice.
Place the cut pieces into a bowl of water to prevent browning.
When ready to cook, drain them thoroughly and pat dry with a towel.
Toast and Grind the Spices: Place a small, dry frying pan over medium-high heat.
Add the chana dal, coriander seeds, and dried red chilies. Toast, stirring frequently, until they darken slightly and become fragrant.
Transfer to a plate to cool.
Once cool, grind into a fine powder using a spice grinder or clean coffee grinder.
Sauté the Aromatics: Heat the oil in a medium, nonstick frying pan over medium-high heat.
Once the oil is hot, add the mustard seeds.
When they begin to pop (this will only take a few seconds), carefully add the crushed curry leaves—they will splutter. Immediately add the chopped onion and stir-fry for 2 minutes.
Reduce the heat to medium and continue to cook for another 2 minutes.
Cook the Poriyal: Add the drained and dried eggplant to the pan and stir for one minute.
Sprinkle in the salt and the freshly ground spice mixture, stirring to coat the eggplant evenly.
Add about 3 tablespoons (45 ml / 1.5 fl oz) of water, stir, and cover the pan.
Cook for 6-7 minutes, stirring occasionally. Uncover, add another splash of water, stir gently, and cover again.
Repeat this process of adding small amounts of water and stirring every 6-7 minutes for a total of 20-25 minutes, or until the eggplant is perfectly tender.
Adjust the heat as needed to prevent sticking.
