Whisk 152 g plain yogurt in a wide bowl, then blend in the marinade spices and 0.5 teaspoon salt. Thoroughly coat 1000 g lamb in the marinade, cover, and refrigerate for roughly 3 hours. When ready to cook, remove the meat from the bowl and set the remaining marinade aside.
In a saucepan, bring 500 g stock and 0.5 teaspoon basil to a boil. Lower the heat and simmer gently for 4 to 5 minutes, then strain through a fine sieve into a separate vessel and reserve.
In a small cup, mix the sauce chilli powder with 2 tablespoons of water until completely smooth.
Warm 92.4 g ghee in a heavy-based pot over high heat, then turn the heat down and add the whole spices. Fry for roughly 30 seconds until the green cardamom pods begin to lighten in colour.
Tumble in 150 g onion and fry for about 4 minutes until pale golden. Add the sauce ginger-garlic paste and stir-fry for 1 to 2 minutes until the liquid cooks off and the onions turn deep golden brown.
Raise the heat to high, add the marinated lamb, and sear for 3 to 4 minutes. Lower the heat, place a lid on the pan, and cook for 20 minutes, stirring now and then and splashing in a small ladle of the warm stock if anything begins to catch.
Uncover and cook on high for 2 minutes to boil away any resting juices. Add the ground coriander and one-quarter of the reserved marinade, stir-frying for about 2 minutes until the liquid evaporates. Continue adding the reserved marinade in three further batches, letting each addition cook dry before pouring in the next.
Stir the rehydrated sauce chilli powder paste into the pan for 1 minute. Add 100 g fried onion paste, drop the heat to low, and cook for 1 to 2 minutes until the fat separates. Pour in 125 ml of the prepared stock, bring to a boil, then cover and simmer over low heat for 3 to 4 minutes.
Remove the lid, set the heat to medium, and fry for 2 to 3 minutes until the sauce reduces. Keep frying the meat while ladling in the remaining stock 2 tablespoons at a time until the lamb becomes completely tender.
Stir in 0.25 teaspoon caramelized onion and fry for 1 minute. Add the finishing spices, rubbing the kasuri methi between your palms over the pot as it goes in. Season to taste with salt and take the pot off the heat.
Use 50% of the weight and stir in near the end of cooking. Adds warmth and depth since it contains ground coriander, but introduces stronger spices like clove and cinnamon.
Use 120% of the weight; melt gently over low heat to avoid burning the milk solids, which will yield a softer, creamier richness rather than a nutty aroma.
Use 1 g ground for 4 g whole (or 1 small pinch per 2 to 3 whole cloves). Add with spice powders; disperses intense warmth quickly, so use with restraint.
Allspice berries
Use 100% of the weight whole in tempering. Imparts a warm, clove-like aromatic profile combined with hints of nutmeg and cinnamon.
Use about a third of the weight (0.5 g ground for a 2.5 cm piece), stirred in with the ground spices rather than fried whole, since the powder burns quickly.
Use 80% of the weight, finely shredded and browned slowly with a pinch of asafoetida. Replicates the bulk and natural sweetness in gravies without allium.
Grate whole nutmeg finely on a microplane; use 80% to 100% of the weight. Freshly grated nutmeg has significantly more aromatic oils and a more vibrant aroma.
Use 100% to 120% of the weight. Mace is nutmeg's outer husk, providing almost identical warmth but with a lighter, slightly more delicate, floral edge.