Wash mushrooms thoroughly. Trim stalks.
Bring water to a boil in a large pot. Add lemon juice and mushrooms. Let it cook for 2 mins. Strain and cool. Slice them/ cut them in half or quarter (depending on the size).
In a medium mixing bowl, add all purpose flour, corn flour, black pepper powder and salt to taste and mix.
Now add mushrooms and coat each slice evenly with the flour mixture.
Heat sufficient oil in a sauce pan for frying the coated mushrooms.
Once fried, place them on an absorbent tissue.
In the same sauce pan, remove excess oil (enough for cooking) and heat.
Add garlic and red chili flakes and cook for 1/2 minute. Then add white parts of green onions and sauté for 2 minutes. Now add onions and stir fry for 2 minutes. Followed by bell peppers. Next add all sauces and cook for 2 minutes.
(This is an optional step) To get a gravy consistency, add about 2 tsps of cornflour to 1/4 cup water. Mix well. Add this to the pan and bring it to a boil. You can adjust the amount of water depending on amount of gravy you need.
Now stir in the pan fried mushrooms, green chillies and salt.
Remove from heat and transfer to serving bowl. Garnish with green parts of green onions & cilantro. Enjoy as a side or with steamed rice, fried rice.