Take the gram flour (besan) in a mixing bowl.
Add the onions, ginger garlic paste, green chilies, carom seeds, coriander leaves, turmeric powder, chili powder and salt.
First add ½ cup of water and start stirring with a whisk.
If the batter seems thick, add a little more water and blend until smooth. Set aside.
Now heat 1 tsp oil in a pan on low-medium heat.
Add the finely chopped onions and sauté until translucent.
Then add the finely chopped mushrooms and sauté until there is no water left.
Transfer to a plate and set aside.
Put a ladleful of batter in the same pan and spread the batter either with the ladle or with the back of the ladle, being careful not to make any breaks.
Over low heat, cook the chilla until the top begins to cook.
Then drizzle 1 tsp oil on the chilla on the edges and also all around.
Turn it over and now cook the other side.
Now put some filling in half of the chilla and gently fold the chilla in half.
Press a bit and finaly transfer the chilla to a plate.
Serve hot with some ketchup or green chutney for breakfast or a tea time snack as well.