Prepare the Lamb: Dice the lamb into small, uniform pieces and rinse thoroughly. Drain well and set aside.
Make the Spice Paste: Combine the chilies, shallots, garlic, candlenuts, galangal, turmeric, coriander, cumin, nutmeg, and white pepper in a blender. Blend into a smooth paste, adding a drizzle of oil if needed to ease blending.
Cook the Paste: Heat 2 tablespoons of oil in a wok or large skillet over medium heat. Add the spice paste and sauté for 5–8 minutes, stirring constantly to prevent burning, until the paste is aromatic and fully cooked.
Add the Lamb: Stir the lamb pieces into the cooked spice paste. Cook for 5–7 minutes, stirring often, until the meat firms up and changes color to white.
Simmer the Curry: Transfer the meat and spice mixture to a large saucepan. Add the hot water, cinnamon, lemongrass, kaffir lime leaves, and salam or bay leaves. Stir well, cover the pan, and cook over medium-high heat for approximately 40 minutes, or until the lamb is tender.
Incorporate Coconut Milk: Reduce the heat to medium, uncover the pan, and add the thick coconut milk. Stir gently to combine. Add the tamarind juice and continue simmering, stirring occasionally to prevent the coconut milk from curdling.
Adjust Seasoning: Taste the curry and adjust the seasoning by adding more salt or sugar if needed. Allow the curry to simmer until the sauce reaches your desired consistency and the flavors have melded beautifully.
Serve: Ladle the hot curry into serving bowls and garnish with crispy fried shallots or onions. For extra heat, serve alongside sambal terasi. Enjoy with steamed rice.