Rinse the whole urad dal and kidney beans and scrub them with your hands; drain the water and repeat this process a few times.
Cover the lentils and beans with a few inches of cold water. Add the baking soda. Soak for 8 hours (or overnight). Drain and rinse several times, until the water runs clear. Note: you can quick soak them by covering them with boiling water for 4 hours.
Select the Sauté setting on the Instant Pot. Add 1 1/2 tablespoons oil, and once the oil is hot, add the cinnamon stick, cardamom pods, cloves, bay leaf, and cumin seeds. Cook for 45 to 60 seconds, stirring frequently, until aromatic and sizzling.
Add the onions with a pinch or two of salt. Cook, stirring occasionally, until the onions are starting to brown, 5 to 6 minutes. Add in a few splashes of water towards the end to pick up the fond and to prevent them from getting too brown.
Add the garlic and ginger, and cook for 1 minute, tossing frequently. Add the tomato paste, nutmeg, coriander, red chile powder, 1 1/2 to 2 teaspoons of kosher salt, and pepper to taste. Stir frequently for about 1 minute. Add the tomatoes and their juices, and cook until broken down and softened, 2-3 minutes.
Pour in the water and scrape up any browned bits to deglaze the pan. Add the soaked lentils and beans, and stir well.
Select the Pressure Cook setting at high pressure for 35 minutes and seal the Instant Pot. Once the 35-minute timer goes off, allow a natural pressure release for 10 minutes, then manually release any remaining steam.
Pour in the cashew cream or coconut milk and select the Sauté setting. Bring to a simmer and simmer for 10 minutes, stirring occasionally to prevent sticking.
Dhungar Method (optional, for smokiness). Bring the Instant Pot close to the stove. Take a small stainless steel or glass bowl and position it in the middle of the cooked dal. If you don't have such a bowl, take a medium onion and cut it in half, around the orbit. Hollow out one half.
Using tongs, take a 1 to 2 inch piece of lump charcoal and hold it directly over an open flame (I use my gas burner). Rotate it from time to time and heat for 2 to 3 minutes, until it turns red hot in spots and has a few white markings. Note: I don't recommend heating it for more than 3ish minutes, as the smoky flavor can become overpowering.
Working as quickly as you can, transfer the charcoal to the small bowl in the dal and pour ½ teaspoon on top of the charcoal (it will start smoking immediately). Cover the Instant Pot with its lid and steam for 2 to 3 minutes. Remove the lid and use tongs to remove the small bowl. Discard the charcoal. Stir the dal again.
Add in the cilantro and lemon juice and season to taste with salt. If it’s a bit too acidic for your taste, add the sugar. Fish out the cinnamon stick and bay leaf.
Make the tadka. Heat the vegan butter in a medium frying pan on the stove over medium high heat. Once melted, add the ginger (if using) and cook for 30 seconds, stirring frequently. Crush the kasoori methi with your hands into the dal, and add the garam masala and red chile powder. Cook for another 30 seconds, swirling the pan frequently. Pour the tadka over the dal and serve.
If making the cashew cream. Cover the cashews with some water in a saucepan. Bring to a boil and boil for 15 minutes. Drain and rinse cashews (Or soak overnight in cool water). Transfer the drained cashews to a food processor. Add the water, lemon juice, and salt. Blend for 3-4 minutes, scraping down as you go, until all cashews are pulverized and the mixture is smooth.Note: you can double this recipe and make it in a high-powered blender (the amount here doesn't have enough liquid for most blenders)