1. Place a small, heavy skillet (preferably cast iron) over medium-high heat 2 to 3 minutes. Add coriander, fenugreek, and peppercorns. Cook, swirling pan, until fragrant and lightly browned, about 2 minutes. Transfer to a bowl; let cool completely. Grind in a spice grinder.

2. Heat oil in a large pot over medium-high. Add mustard seeds and cinnamon. As soon as mustard seeds pop, add chicken in a single layer (work in batches, if necessary). Cook until browned on all sides, about 5 minutes per side. Set pieces aside on a plate as they are done.

3. Add onions and garlic to pot and reduce heat to medium. Cook, stirring occasionally, until onions are golden brown, about 10 minutes. Add ginger and tomato. Cook until tomato is soft, about 3 minutes. Add ground toasted spices, turmeric, cayenne, 1 1/2 teaspoons salt, and lemon juice. Return chicken to pot, along with any accumulated juices.

4. Remove thick coconut cream from top of coconut milk; set aside. Stir remaining contents of can into pot. Add enough water to fill can again (1 1/2 cups) and add to pot. Bring to a boil, then reduce heat to low and simmer, partially covered, and stirring occasionally, until chicken is cooked through, 20 to 25 minutes.

5. Stir reserved coconut cream; add to pot along with chiles. Stir once or twice to warm through; remove from heat. Remove chiles and cinnamon stick, if desired. Serve, with rice, yogurt, and chutney.