Grind together pepper, green chilli, ginger, garlic, coriander with 2 tbsp water to a fine paste. Add this ground masala, lemon juice and salt to the cleaned mutton pieces. Marinate for one hour.
Saute the onions until the onion turns golden brown. Add all the masala powders and mix well. Add a little water to mix everything well. When the oil starts appearing, add tomato and salt. Mix well. After 5 mins, add the marinated mutton pieces. Mix well. Add one cup of water and cook till mutton is done.
Wait till the water dries up and mutton is covered with masala. Garnish it with pepper and onion rings.