While the mutton is resting, peel and cut the onions into thin slices.
Take a blender and make a paste of the ginger, garlic, and 4-5 green chilis. Keep them aside.
Next, take a large Kadhai and add oil.
Keep the flame on medium and let the oil heat until it smokes a little.
Now, to the oil, add the bay leaves, dried red chilis, cloves, green cardamom, black cardamom, and the cinnamon stick (break into 2 pieces).
Stir all these until fragrance comes out of the aromatics.
Next, add the sliced onions.
Stir and fry them until golden brown in color. Keep the flame on medium. This should take around 12-15 minutes.
To this add the ginger, garlic, and green chili paste.
Combine everything nicely and fry them for about 5 minutes or until the raw smell is gone.
By now, the onions will start to caramelize.
Take a small bowl and add the cumin powder, coriander powder, and Kashmiri red chili powder.
Add 2 tbsp of water and make them into a slurry.
Add the slurry to the kadhai. Mix nicely.
Fry everything until the oil starts separating from the masala.