Heat oil in a wok, add the curry paste and stir well. Stir in the coconut milk, stock, turmeric, fish sauce, sugar and tamarind water. Simmer for 5 minutes.
Add the fish and simmer for 6-8 minutes. Stir in the tomatoes and peppers. Simmer over low heat for 10 minutes until thickened.
Ladle into a serving bowl and garnish with coriander leaves.