Grate onion, strain it in a colander, and discard the juice by keeping the grated onion in a colander. The Grated onion needs to be completely dry before adding to the mince.
Soak saffron in 3 tablespoons warm water for 15 minutes. Crush the strands slightly to release the flavor and color.
In a large bowl, mix together the mutton mince, fat mince, grated onion, crushed black pepper, turmeric powder, soaked saffron along with its water, and salt. Mix well for 5 minutes till the mixture is smooth and all ingredients are well combined.
Marinate the mince mixture for 4 to 5 hours in the refrigerator.
Preheat oven to 250 degrees.
Dip hands in water, take a handful of the mince mixture, and shape it around a flat kabab skewer. Flatten the kabab with dents as shown in the picture below.
Place the kebabs in the oven close to the top flame. Grill the kebabs for 10 minutes on each side. Baste with melted butter while cooking.
Serve hot with saffron rice and grilled tomatoes.
Wash and soak the rice for 30 minutes. Heat enough water and salt to cook the rice. Add the soaked rice and drain when cooked. Return the cooked rice back to the saucepan. Add 2 to 3 tablespoons butter and soaked saffron strands to the rice (see the pictures given below). Cover the saucepan and cook the rice on low flame for 5 minutes (dum cooking).
Serve the rice hot along with the kababs and grilled tomatoes.