PREPARE THE SHATKORA:
If using frozen shatkora, defrost in cold water for 1 hour. Cut the shatkora into wedges, then chop each wedge into 3-4 pieces, removing any seeds. Set aside. The rind is where the flavor lives—include all of it.

BUILD THE FLAVOR BASE:
In a large heavy-bottomed pot or Dutch oven, heat the oil over medium heat until shimmering. If using mustard oil (traditional for Bengali cooking), heat until it just begins to smoke, then reduce heat—this mellows its pungency.

Add the bay leaves, cinnamon stick, black cardamom, green cardamom pods, cloves, star anise, and peppercorns. Fry for 30-45 seconds until fragrant and the spices begin to sizzle. Watch carefully—burnt spices turn bitter.

Add the sliced onions and a pinch of salt. Cook over medium heat, stirring frequently, for 10-12 minutes until deeply golden brown. Critical: This is where patience pays off. Properly browned onions create the foundation of flavor. Do not rush this step.

Stir in the minced garlic, ginger, and green chillies. Cook for 2 minutes until fragrant and the raw smell dissipates.

ADD THE LAMB AND SPICES:
Reduce heat to medium-low. Add the turmeric, cumin, coriander, and Kashmiri chilli powder. Stir constantly for 1 minute to toast the spices without burning. If the pan seems dry, add a splash of water to prevent scorching.

Increase heat to medium-high. Add the lamb pieces and salt, stirring to coat thoroughly with the spice mixture. Cook for 5-7 minutes, turning occasionally, until the lamb is lightly browned on all sides.

Pour in 1½ cups (350ml) of water, scraping up any browned bits from the bottom of the pot. These fond bits are concentrated flavor.

SLOW COOK TO TENDERNESS:
Bring to a boil, then immediately reduce to a gentle simmer. Cover and cook for 1 hour, stirring every 15-20 minutes to prevent sticking. Critical: Control your heat. A violent boil will make the curry catch on the bottom; a gentle simmer preserves flavor clarity.

After 1 hour, the lamb should be becoming tender. If the liquid has reduced significantly, add another ½ cup of hot water.

Stir in the prepared shatkora pieces. The citrus needs time to cook down and infuse the curry, but adding it too early makes the dish overly bitter. Cover and continue simmering for 30 more minutes.

FINISH THE CURRY:
After 30 minutes with the shatkora, check the lamb—it should be fork-tender and nearly falling off the bone. If you prefer more gravy, add ½-1 cup of hot water and bring to a gentle boil. For a thicker sauce, simmer uncovered for 10 minutes to reduce.

Remove from heat. Stir in the finishing garam masala and most of the fresh cilantro, reserving some for garnish. Taste and adjust salt as needed.

Let the curry rest, covered, for 10 minutes. This allows the flavors to meld and the shatkora to fully integrate.

Transfer to a warm serving dish and scatter with remaining fresh cilantro. Serve immediately alongside pilau rice, dal, and rice flour rotis.