Prick the potatoes in several places with a fork.
Add the onion, garlic, ginger and tomatoes to a blender or food processor and puree until smooth. Set aside.
To make the creamy cashew sauce, add the cashews and ½ cup water to the blender and puree until smooth. Set aside.
Press the sauté button and add oil and the blended onion and tomato mixture. Stir-fry for 8-10 minutes until the mixture has thickened.
Add the spices and the potatoes and mix well, then add ½ cup water to the pot.
Secure the lid, close the pressure valve and cook for 8 minutes at high pressure.
Open the valve to quick release any remaining pressure.
Stir in the cashew sauce, fenugreek leaves and cream if using.