Step 1Combine the curry leaves, mustard seeds, cumin seeds, fenugreek seeds, peppercorns, cloves and cardamom pods in a skillet over medium heat and cook, stirring, until fragrant, 1 1/2 to 2 minutes.
Step 2Cool slightly. Grind to a powder in a spice grinder and set aside.
Step 1Toss the chicken with one-fourth teaspoon salt, the pepper and lemon juice and let stand at room temperature for 30 minutes.
Step 2Combine the oil, mustard seeds, red chiles, cardamom, green chile and curry leaves in a large saucepan over medium-high heat. Cover and cook until you hear the mustard seeds crackle, 1 to 2 minutes. Add the ground spice mix and cook, stirring, 30 seconds. Add the shredded coconut and cook, stirring, 30 seconds.
Step 3Add the chicken and cook, stirring, until opaque, about 3 to 5 minutes.
Step 4Add the coconut milk and one-half teaspoon salt. Bring to a boil, reduce the heat and simmer, partially covered, until the chicken is tender, 25 to 30 minutes. Stir two or three times during the last 10 minutes of cooking and scrape the bottom of the pan to keep the sauce from sticking. Taste for salt, add more if desired and serve hot.