Prepare the spice mix by combining garlic, ginger, turmeric, garam masala, cumin, cayenne, chilli flakes, and mustard seed in a small bowl.

Prepare the vegetables: chop tomatoes, trim green beans, and slice onions.

Chop the chicken thigh fillets into 3cm pieces.

In a large, heavy-based pot, heat a little oil over high heat.

Brown the chicken in batches (about 3 batches) and set aside.

Add the sliced onion to the pot and fry for approximately 3 minutes.

Add the spice mix and fry for another 2 to 3 minutes, stirring continuously to release the aromas.

Return the browned chicken to the pot, then add chicken stock and chopped tomatoes.

Bring the mixture to a boil, then reduce the heat and simmer with the lid on for 30 minutes.

Remove the lid, add coconut milk, and simmer for an additional 5 minutes (lid off). Increase the heat slightly as the lid is off.

Add the green beans and continue to simmer for another 5 minutes, or until the beans are slightly softened.

Serve hot with boiled rice.