Place chicken in a large bowl, and season with turmeric powder, coriander powder, black pepper, chili powder, and salt. Cover bowl, and refrigerate for 1 hour.
Heat oil in a large pan over medium heat. Fry mustard seeds, fenugreek, onion, cumin seeds, and curry leaves in oil for about 3 to 4 minutes. Stir in garlic and ginger pastes, and cook for another 2 minutes. Add chicken and water, stir, and cover with lid. Cook for 20 to 25 minutes.
Stir in coconut milk, and cook until almost dry. Stir to keep the chicken from sticking to the bottom of the pan. Stir in lime juice, and cook until dry.