Pressure-cook the split yellow peas and cabbage with enough water to cover and turmeric. If you use an Indian pressure cooker that "whistles" allow the lentils to cook for three whistles. If cooking in a saucepan, cover by an inch of water and cook 30 minutes or until the dal is really soft. If cooking in an Instant Pot, set the pressure to high for 15 minutes.
Heat 1/2 tsp of the oil and add the masala ingredients. Fry them until the dals turn golden, remove to a blender, and grind into a smooth paste along with coconut or coconut milk.
Heat the remaining oil in a saucepan. Add the mustard seeds and curry leaves and when the mustard sputters, add the dal and masala and mix. Add water if too thick.
Bring the dal to a boil, lower the heat to a simmer, and cook for another five minutes. Add salt to taste.