In a large bowl combine yogurt, ginger paste, garlic paste, red chili powder, turmeric and 2 tsp kosher salt. Add the lamb pieces and coat thoroughly. Cover and refrigerate for at least 2 hours, preferably overnight. This tenderizes and infuses flavor.

Spice Prep

While lamb marinates, toast coriander, cumin, fennel seeds and dried red chilies in a dry skillet over medium heat for 1–2 minutes until aromatic; cool slightly then grind to a fine powder. Crush mace or grate a very small pinch of nutmeg if using. Lightly crush cardamom pods.

Puree tomatoes if using fresh and measure onions, ginger and garlic as noted.

Cooking the Curry Base

Heat a heavy-bottomed pot or Dutch oven over medium-high heat until hot. Add mustard oil and heat until it just starts to smoke lightly (if using mustard oil). Reduce heat to medium. Add ghee, bay leaves, cinnamon stick, cloves, black peppercorns and crushed cardamom pods. Sauté for 30–45 seconds until fragrant.

Add the finely sliced onions and a pinch of salt. Cook, stirring frequently, until onions turn deep golden brown, about 12–18 minutes. If they brown too quickly, lower the heat. This step builds the curry's depth of flavor—be patient.

Once onions are deeply browned, add the julienned fresh ginger and sliced garlic. Cook 2–3 minutes until raw aroma diminishes and the mixture is glossy.

Add the tomato puree and cook, stirring occasionally, until the oil begins to separate from the masala, about 8–10 minutes.

Stir in the ground spice mix (toasted coriander, cumin, fennel, dried chilies) and cayenne if using. Cook 1–2 minutes to bloom the spices.

Cooking the Lamb

Remove marinated lamb from the refrigerator and let come closer to room temperature (10–15 minutes). Increase heat to medium-high and add the marinated lamb pieces to the pot in batches if necessary to avoid crowding. Brown lamb on all sides for 6–8 minutes; this may release some marinade — stir to incorporate browned bits into the masala.

Once lamb is well combined with the base, add 2 cups water or lamb stock, crushed mace (or nutmeg) and bring to a simmer. Scrape any browned bits from the bottom of the pot.

Reduce heat to low, cover partially (lid slightly ajar) and simmer gently until lamb is tender and sauce is thickened, about 1.25–1.5 hours. Stir occasionally and adjust heat to maintain a gentle simmer. If using a pressure cooker, cook for about 20–25 minutes after the first whistle, then release pressure and check tenderness.

Finishing

When lamb is tender and sauce has reduced to a rich, slightly oily curry, taste and adjust salt. Stir in crushed kasuri methi and chopped cilantro. Simmer uncovered for 3–4 more minutes to meld flavors.

Turn off heat and let the curry rest 5–10 minutes before serving to let flavors settle. Serve Lal Maas hot with lemon wedges on the side and steamed basmati rice or hot rotis.