Set the Instant Pot® on Sauté mode and heat the oil. After about 3 minutes, add the cumin seeds and sauté until the seeds begin to sizzle. Add the onions and cook for 3 to 4 minutes, until they begin to wilt and soften. Add the garlic and ginger and cook for another 2 minutes. Stir in the tomatoes, garam masala, cayenne pepper powder, salt, and sugar, and cook for 5 minutes.
Press Cancel to turn off the Sauté mode, close the lid, and put on Manual Pressure mode for 7 minutes.
When cooking time is complete, allow for Natural Pressure Release for 5 minutes, then do a Quick Release for any residual pressure.
Open the lid and stir in the coconut milk. Using an immersion blender, puree the sauce until it is relatively smooth.
Stir in the fenugreek leaves, set the Instant Pot® on the Sauté mode, and heat through for 2 minutes.
Cool the sauce and store in the refrigerator for up to a week, or freeze in small containers and use as needed.