Select the Sauté setting on your Instant Pot and heat up the coconut oil. Once it's shimmering, add the cumin seeds and fry for 1-2 minutes, or until the seeds are sputtering.
Cook the diced onion for 3 minutes. Then add the garlic, ginger, serrano pepper, coriander, garam masala, red chile powder, turmeric, and black pepper. Cook for 1-2 minutes, stirring frequently and scraping up any bits that are stuck.
Pour in the vegetable broth to deglaze the pot, using a wooden spoon or scraper to scrape up any browned bits on the bottom of the pot. Add the lentils and 1 teaspoon sea salt. Stir to combine all of the ingredients. Select the Cancel setting.
Secure the lid of the Instant Pot and seal. Select the Pressure Cook (or Manual, depending on your model) setting and cook at high pressure for 6-8 minutes, depending on your desired firmness (I prefer 6 minutes).
Once the timer is up, allow a natural pressure release for 10 minutes before switching the pressure release valve from Sealing to Venting. Open the Instant Pot and stir in the vegan butter (if using), stirring until it's melted and mixed through. The butter adds more creaminess and richness to the lentils, but they are still good without it.
Serve the lentils with fresh cilantro and coconut yogurt, if desired.