Turn on the Instant Pot and set to Saute mode. Once it's heated, add in oil, cumin seeds, mustard seeds, and dry fenugreek seeds.
Once the cumin seeds start to sizzle, add in the chopped onions followed by ginger garlic paste. Fry for a few minutes, stirring occasionally, till onions start to brown.
Add in chopped tomatoes and let it cook for a couple of minutes till the tomatoes start to soften and pulp.
Add the fenugreek leaves next and saute.
Add in spices and salt, and give it a quick mix.
Mix in the boiled lentils and water and let it come to a quick boil.
Serve hot with rice.