Preheat the oven to 350F/180C. Season the chicken thighs with salt and pepper. In a large pan heat the oil and brown the chicken thighs on high heat on each side until golden but not cooked all the way through, then remove to a plate.
Lower the heat and add the onion and ginger, cook for 5 minutes, then add garlic, turmeric, coriander, cumin and the chilli powder, cook while scraping the bottom of the pan and stirring the whole time for 1 minute or so.
Add the rice and cook while stirring for 1 minute, then add the water, coconut milk, salt and frozen peas stir to combine, turn up the heat and bring to a boil.
Return the chicken with the juices, that collected at the bottom of the plate, to the pot, cover with a lid and put in the oven for 30 minutes or until the rice is done. By the end of the cooking time, the liquid should be completely absorbed, producing light and fluffy rice. (If there is still remaining liquid after 30 minutes, cook for 10 minutes longer uncovered.) Serve sprinkled with chopped cilantro/coriander and sliced green onions.