Heat oil in a pan and fry onion till golden brown.
Add the ginger garlic paste and fry till the raw smell has vanished from it. (about 2-3 minutes)
Add the mutton pieces and fry really well till all the water has dried up from it and the mutton has browned a little.
Next throw in the red chili powder coriander powder, salt, cardamom, cloves, cinnamon, cumin seeds, shahi jeera, black pepper corns, bay leaf and cup of water.
Cook on low heat till the mutton is soft and tender. (Alternatively cook in pressure cooker for 2 - 3 whistles).
Once the mutton is done, add the yogurt and cook till the yogurt is well incorporated into the masal.
Add the green chili, coriander leaves and garam masala powder. Stir well. And cook on low heat till the oil starts floating on top.
Add lemon juice, mix and remove from heat.
Serve hot with roti or rice.