Heat a pan or kadai. Take all the whole spices mentioned under the "whole spices for kadai masala' list in the pan.
Dry roast all the whole spices on a low flame till they become aromatic. Stir them often while roasting.
Once the spices cool down, add them to a grinder jar or a spice or coffee grinder. Grind to a fine powder.
Remove in a plate and keep the kadai masala aside.
Switch on the instant pot. Press the sauté button for 15 to 20 minutes on the normal mode. Add oil in the steel insert of the instant pot.
When the oil becomes hot, add the chopped onions. Saute stirring often, till the onions soften and become translucent.
Then add ½ teaspoon garlic paste, 1 teaspoon finely chopped ginger, 1 slit green chilli or serrano pepper.
Mix and sauté for 3 to 4 seconds.
Add 1 cup finely chopped tomatoes and sauté till the tomatoes soften and become pulpy.
Add sliced button mushrooms.
Mix very well and deglaze the pot. Scrap any stuck bits of ingredients from the bottom of the pot. The moisture from the mushrooms help in deglazing.
Sauté for about 3 minutes.
Add turmeric powder and salt as required. Mix again well.
Add ½ cup water. Deglaze if required.
Press cancel and press the pressure cook or manual button. Set the timer to pressure cook for 3 minutes on high pressure.
Then do a quick pressure release by lifting the valve. Open the lid.
Then add capsicum and ground kadai masala and 1 teaspoon kasuri methi (crushed). Mix very well. You can reserve ½ teaspoon of kadai masala for garnish. Kasuri methi is dried fenugreek leaves. If you do not have kasuri methi then skip it.
Press the sauté button for 5 to 6 minutes on the normal mode.
Sauté for 5 to 6 minutes. Stir often. You can reduce to the low setting if the masala sticks to the pan or heat becomes too much.
Sauté till the capsicum is half cooked. The capsicum should have some crunch in them.
Add 1 to 2 tablespoon chopped coriander leaves. Mix well.
Serve instant pot kadai mushroom garnished with some coriander leaves and ginger julienne (optional). Serve with chapati, tandoori roti, naan or dinner rolls or bread. Also sprinkle the kadai masala, if you have reserved it while serving the dish.
Cleaning mushrooms: Rinse or wipe dry or simply wipe the mushrooms with a clean kitchen towel. Then slice or chop them.
Use less red chillies if they are too spicy and hot.
Fresh edible mushrooms of any variety can be added.
If the dish looks too dry after cooking, then add some hot water.
Kasuri methi (dried fenugreek leaves) can be skipped if you do not have it.
Reduce to low sauté setting if while sautéing the ingredients stick to the pot.
Any bell pepper variety can be added in the recipe.