"I first tried this curry in a restaurant in Bangalore. I loved it so much that I asked all my friends if they knew anyone from Mangalore who could share the recipe with me. Finally, one of my friends came through. Below is an adaptation of her mother's recipe. If you like peppery curries and tamarind, you are sure going to love this style of curry. Serve with steamed plain rice or with chapati."
Heat 1 teaspoon vegetable oil in a small skillet over medium heat. Add peppercorns, poppy seeds, cloves, cinnamon stick, dried chile peppers, cumin seeds, and black cardamom; toast until fragrant, 2 to 3 minutes. Transfer to a spice grinder, add grated coconut, and grind into a paste.
Combine onions, garlic, and ginger in a food processor; grind into a paste.
Heat 2 tablespoons vegetable oil in a stovetop pressure cooker. Add onion paste; cook and stir until golden brown, about 5 minutes. Pour in pureed tomatoes; cook and stir until darkened, 4 to 5 minutes. Stir in turmeric and salt. Add lamb; cook and stir until evenly coated and starting to release some juices, about 10 minutes.
Stir coconut paste, potatoes, water, tamarind paste, and sugar into the pressure cooker. Bring to a boil. Cover, bring to high pressure according to manufacturer's instructions, and cook, about 10 minutes. Reduce heat and continue cooking, about 15 minutes more.
Release pressure according to manufacturer's instructions. Serve curry garnished with cilantro leaves.