Whisk 127 g plain yogurt with the spices for the yogurt and 1 tsp chilli powder in a bowl until smooth.
Process 200 g onion in a blender to a fine paste, adding a splash of water only if required to loosen the blades.
Crush the saffron and let it steep in 1 tbsp warm water for 5 minutes, then pound in a mortar or blend into a paste.
Warm 46.2 g ghee in a heavy pan set over medium heat, add the ginger and garlic pastes, and saute for 1 to 2 minutes until dry.
Add the onion paste and cook for 5 minutes until droplets of fat break out on top. Take the pan off the flame, thoroughly mix in the seasoned yogurt, return to the heat, and fry for 2 to 3 minutes until oil separates.
Pour in 500 g stock and salt to taste, bring to a rapid boil, then lower the heat to medium. Drop in 2 cans drained water chestnuts, return to a boil, then simmer gently on low, stirring occasionally, until the chestnuts are heated through.
Add 500 g bamboo shoots, bring back to a boil, and simmer until the gravy reaches your preferred thickness. Fold in 1.5 tsp shahi masala and the prepared saffron paste, remove from the heat, and check the seasoning.
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.
Steep a tiny pinch (0.1 g per 2 g turmeric) in 2 tbsp warm water; use to match the rich golden hue. Contributes an aristocratic, honeyed floral flavour rather than earthy bitterness.
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.
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 100% of the weight. Add an extra pinch of salt and simmer with a bruised bay leaf or a slice of ginger; the gravy will taste cleaner but slightly less savoury.
Use 50% of the weight mixed with equal parts ground coriander and a pinch of ground cinnamon, ground cloves, and ground green cardamom. Sprinkle near the end for a warming finish.