Select the saute mode on the instant pot and heat coconut oil. Add cumin seeds and cook for 30 seconds. Add the finely chopped serrano pepper, ginger and garlic and cook for a minute. Add finely diced onion and pinch of salt. Cook for 3 minutes till onion turns slightly soft.
Add turmeric powder, red chili powder, curry powder, garam masala, coriander powder and salt. Cook for 30 seconds. If the spices are sticking to the pot, splash some water.
Add the pureed tomato and tomato paste and cook for a minute. Add the washed red lentils, water, coconut milk and cashew cream
Mix all the ingredients, making sure nothing is stuck to the bottom of the pot. Cancel the saute mode, secure the lid and adjust the vent to sealing position. Pressure cook on high for 4 minutes.
After the 4 minutes timer has completed, wait for 10 minutes to release the pressure.
Add the coriander leaves and lemon juice. Mix the curry, taste and adjust the salt.
If you feel the curry is too thick, add some hot water to it.