Heat the sunflower oil in a large casserole dish over a medium heat until hot. Sweat the onion, garlic and ginger for 6-7 minutes, stirring occasionally until they start to soften. Add the ground spices, turmeric, chilli powder, caster sugar and some seasoning to the dish and stir well.
Cook for a further minute, stirring occasionally, then add the whole okra and chopped tomatoes, stirring well to combine. Cover with the water and coconut milk, stir, then bring the mixture to a simmer. Simmer for 20-25 minutes until the okra is soft and tender. Adjust the seasoning as necessary. Serve in bowls.