Heat a tablespoon of oil in a pressure cooker or a heavy-bottomed saucepan or in the liner of the Instant Pot set to the "saute" function. Add the moong dal and saute until very aromatic and a couple of shades darker. Add the rice and saute for a couple of minutes until the grains turn opaque.
Add 4 cups dairy-free milk to the rice and lentils. Mix and cook until the rice and lentils are very, very soft. If doing this in a saucepan you will need about 30 minutes. Cover the pot and stir occasionally during cooking. Add more water or milk if the mixture dries up before it has cooked. In a pressure cooker that whistles, cook for four whistles. In the Instant Pot cook for 15 minutes on manual pressure.
Add a quarter cup water to a saucepan, bring to a boil, then add the jaggery. Let the jaggery mixture come to a boil.
Once the jaggery boils, let it continue cooking for six more minutes over medium-low heat. This is really key because you want the jaggery to lose its raw taste. Don't let the jaggery cool down once it's done because it will harden up as it stands.
About five minutes before the jaggery has cooked, heat a tablespoon of oil in a large wok or kadhai or skillet. Add the cashews and stir-fry for a couple of minutes over medium heat until the cashews are a light golden-brown.
Add the cooked rice and dal mixture to the wok with a cup of milk or water. Mix thoroughly and bring to a boil over medium high heat.
Pour in the melted jaggery and mix it into the rice and dal mixture. Bring the pongal back to a boil. If the mixture looks dry add some more water or milk.
Once the pongal has been cooking for about five minutes, stir in the ground nutmeg and ground cardamom.
Continue cooking the pongal a couple more minutes, stirring frequently, until the mixture has thickened and has the consistency of a thick pudding. Add a very tiny pinch of salt at this point, to accentuate the sweetness of the pongal. Turn off the heat and stir in the pure vanilla extract.
Heat a small skillet and add a teaspoon of oil. Roast the raisins in the oil for just a minute until puffy but not burnt. Add them to the pongal and stir in.
Serve the sweet pongal warm or at room temperature.