Heat three tablespoons of oil in a pan and sauté the onion and chillies for three minutes.
Stir in the ginger, garlic, chilli powder, coriander, turmeric, and salt.
Add the chicken and fry on low-to-medium heat for eight minutes until lightly browned.
Add the tomatoes and potatoes then cook for two minutes.
Pour in 100ml of coconut milk and simmer for six minutes.
Add the remaining coconut milk and 200ml of boiling water.
Simmer for 10 minutes until potatoes are tender and chicken is cooked.
Heat the remaining oil in a separate pan and add curry leaves and shallots.
Fry for five minutes until golden brown.
Sprinkle garam masala over the stew and swirl in two tablespoons of extra coconut milk.
Garnish with fried shallots and curry leaves and serve hot with basmati rice.