Step one
Place chicken in bowl with curry powder, ground chile, and vinegar. Mix well with hands and set aside for 30 minutes, or marinate the chicken overnight for optimum results.
Step two
In a large pot, heat oil over medium-high heat until it shimmers. Once hot, add onions, garlic, ginger, curry leaves, lemongrass, cardamom pods, cloves, and cinnamon. Fry, stirring frequently, until onions are golden brown.
Step three
Add chicken pieces one by one, stirring occasionally until chicken is browned. Add a little water to the bowl that contained chicken and slosh around to catch any remaining marinade and add to pot.
Step four
Stir in coconut milk and salt and bring to a boil. Reduce heat, cover and simmer for about 30 minutes. Stir in tomato paste and simmer for additional 15 minutes, then taste again for seasoning and serve.