Blend onion, garlic, ginger, chile with a few tablespoons of water into a puree in a blender.
Put Instant Pot on Saute. Add oil. When the oil is hot, add the onion puree. Cook for 3 mins, stir occasionally to avoid burning. (You can also saute without oil. Use broth and use finely chopped onion ginger garlic so that they dont stick)
Meanwhile, blend tomatoes in the same blender until smooth and set aside.
Add the spices and mix in. Add the pureed tomato and mix well to pick up and mix the sticking onion mixture so it doesnt burn while under pressure.
Add the mushrooms and salt and mix well. (You can add other veggies or 1 cup cooked chickpeas/beans at this point). You dont need additional liquid as the mushrooms and veggies if using, will release moisture during cooking.
Cancel saute. Close the lid and Pressure cook for 6 mins on high pressure. Once done, Release the pressure after 10 mins.
Add the peas, spinach, cashew cream, cayenne if using, and sweetener if using. Put the pot on saute and bring the mixture to boil. Taste and adjust salt, spice, flavor. Cancel saute and serve garnished with lemon juice, cilantro. Stove top version here.
Nut-free: To make the sauce without nuts, use pumpkin seeds or silken tofu to make the cream or use plain unsweetened non dairy yogurt or coconut cream(thick coconut milk from a can of full fat coconut milk), or use just water for a non creamy curry.Fenugreek seeds or ground: Use a 1/4 tsp fenugreek seed powder instead of 1 tsp fenugreek leaves. If you have seeds, grind them and use a 1/4 tsp of the ground.Doubling: Double everything except heat(hot green chile,, cayenne). Pressure cook for 6-7 mins. Nutrition is 1 of 3 serves