Peel the onion and garlic, then roughly chop the onion for the broth.

Add 1.5 lb lamb or goat meat and the chopped onion to a large cooking pot.

Add cumin seeds, coriander seeds, garlic, ginger paste, 2 tsp salt, and 4 cups water to the pot.

Bring the broth to a boil, then cook it for 20 minutes.

Remove the cooked meat from the broth and set it aside.

Strain the broth through a fine-mesh strainer and reserve it for the pulao.

Rinse 2.5 cups long-grain basmati rice until the water runs mostly clear.

Soak the rinsed long-grain basmati rice in water for at least 30 minutes.

Thinly slice the remaining onion while the rice soaks.

Heat 1/2 cup cooking oil in a large cooking pot over medium heat.

Add black peppercorns, whole cloves, green cardamom pods, black cardamom pods, bay leaves, and cinnamon stick to the hot oil.

Sauté the whole spices for 1 minute until fragrant.

Add the thinly sliced onion and cook it until light golden brown.

Add the cooked lamb or goat meat and fry it with the onion for 4 to 5 minutes over medium heat.

Stir in the remaining 1/2 tsp salt and all reserved broth.

Drain the soaked long-grain basmati rice thoroughly.

Add the drained long-grain basmati rice to the broth and gently stir once.

Taste the cooking liquid and adjust the salt only if needed.

Cook the rice uncovered over high heat until most of the broth has evaporated.

Sprinkle 1 tsp black cumin seeds over the rice when a small amount of liquid remains.

Cover the pot with a paper towel and place the lid tightly over it.

Steam the pulao over low heat for 15 to 20 minutes.

Fluff the mutton pulao gently with a fork before serving.

Serve the mutton pulao hot with green chutney.