Start the instant pot in sauté mode and let it heat. Add oil, cumin seeds to it. When the cumin seeds start to splutter, add chopped onion, ginger, garlic and chili pepper. Sauté for 3 minutes.
Add chopped tomatoes and spices. Stir and sauté for another 2 minutes.
Drain the soaking water from kala chana. Add kala chana and 2 cups of fresh water to the instant pot. Change the instant pot setting to bean/chili mode. This will automatically set the timer to 30 minutes.
When the instant pot beeps, let the pressure release naturally (NPR). If the pin has not dropped after 20 minutes, release the pressure manually. Open the instant pot and add amchur (dry mango powder) to it. Stir well for a minute.