First, make a coarse paste of all the ingredients mentioned under make a coarse paste in the ingredient list without adding water using a blender or a mortar and pestle.
Heat a stir fry pan and add 1 tbsp oil and ½ tbsp butter.
When the oil is hot, add bay leaf, cinnamon stick, curry leaves, and turmeric powder and saute for a few seconds.
Now add diced onions along with ½ tsp salt to help onions cook faster. Saute them until translucent while stirring in between. Do not cover the pan.
Add cubes of green bell pepper and stir well.
After 3 to 4 mins add mushroom pieces and mix well.
Add salt to taste and cook for another 3 to 4 mins until mushrooms and bell peppers are half done.
Now move them to the sides of the pan and make a well in the middle.
Add ½ tbsp butter to the well, and add the coarse masala paste in the butter, fry for a few seconds, and then mix everything together.
Now cook for another 3 to 5 mins until they are done. Do a taste check for salt. Make sure not to overcook as the mushrooms and bell peppers should have a bite to them when done.
Garnish with cilantro and serve hot with rice or roti with yogurt on the side.