Prefer skinless peanuts as it saves a lot of time. But if these are skinned, then put them on a plate, heat it in a microwave for 4 minutes - 1 minute at a time. So you put for 1 minute, take it out, reshuffle it, repeat 3 more times. Let it cool, then rub the peanuts between the palm of your hands, the crisp skins will come off easily. If not, you may have to repeat heating in microwave for some more time. Separate the peanuts and the skin.
I am giving the recipe here using microwave oven. But the same can be done on a stove top as well.
Line a wide bottomed, microwave safe plate with a parchment paper. The parchment paper is not necessary but it will save you the plate cleaning time later. You are welcome :) Put the skinless peanuts in the lined plate, making sure all the peanuts are in single layer.
Take 1 to 2 tablespoon of water, add ½ teaspoon of salt, mix it such that the salt is completely dissolved in water. Drizzle it the water on the peanuts, mix, spread the peanuts in a single layer on the lined plate. Microwave for about 8-10 minutes, at intervals of 1 minute each. Meaning, microwave it for a minute, then mix well, microwave again, repeat. After about 4 minutes, sprinkle the black salt, chaat masala, turmeric powder and mix the peanuts, continue the microwaving process. Make sure the peanuts don't get burned. It only takes a split second for this to happen. If need be after a few minutes, you can microwave it for 30 second at a time instead of a minute, just to be extra sure.
After about 7-8 minutes, keep the plate on the side. Once it cools down, the peanuts would turn crunchy. If not, it might require 1-2 minutes more microwaving in 30 seconds at a time. The masala peanuts are ready.