• Clean the mushrooms by rubbing them with a damp cloth. If the mushrooms are small, leave them whole. You could keep the stems however if the mushroom stems have any dry or tough ends, trim them with a knife. If the mushrooms are rather large, half them.

Make Browned Onion Paste

• Add mustard oil to a cooking pot or kadai (indian wok). 
• For the next 6 to 8 minutes, on medium heat let the onions brown. Don't stir too much else the onions start releasing their water instead of browning. You could use this time to make tomato puree.
• When the onions are golden brown, using a slotted spoon transfer them to a blender jar. Reserve some onions for garnishing later. Add yogurt to the blender jar and make a coarse paste. Set aside.

Make Mushroom Masala Sauce

• To the remaining oil, add the whole spices. Let crackle for few seconds. 
• Reduce to low flame and introduce the ginger and garlic. Saute for 10-15 seconds taking care not to burn. Add the powdered spices next along with a splash of water. Fry the spices for a minute in oil. 

  Tip - I save the water in which I boiled the tomatoes and use while making the sauce. 
• Next goes in the tomato puree and sugar. Fry the tomatoes and spices together for good 2-4 minutes or until you see bubbles of oil separating on sides. 
• Reduce the flame to low and add the onion yogurt paste we made. Immediately start stirring to avoid yogurt from curdling. Fry for 1-3 minutes to cook out the moisture of yogurt. You will see that the masala is becoming shiny. 
• Add the mushrooms and sprinkle salt. Stir to coat the mushrooms in the masala. We will fry the mushrooms with masala for good 2-3 minutes to get them started. Slowly they will warm up, start absorbing the flavors of the masala and you will notice water of the mushrooms starting to release.Then, add about ½ cup to ¾ cup hot water (add as required).

  Tip - Remember that mushrooms are going to release their moisture as they cook and could get pretty watery, add water depending on how you like the consistency.
• Cover the pot now and let cook for 10-12 minutes or until the mushrooms are cooked through.Finish with garam masala, amchoor and kasuri methi. Add chopped cilantro and browned onions to garnish this delicious curry.
• Serve garnished with reserved fried onions.
• INSTANT POT & PRESSURE COOKER INSTRUCTIONS

  On IP saute mode, cook steps noted above and make the masala base and add mushrooms. Saute for 2 minutes with masala. Add water, close the lid of the instant pot or pressure cooker. Cook on high pressure for 5 minutes in sealed position. Let pressure release naturally for 4-5 minutes. Finish the curry with garam masala, amchoor and kasuri methi. Add chopped cilantro to garnish.

  In pressure cooker, cook for 2 whistles on medium flame after you have added the mushrooms. Let pressure release naturally.