For the spice mixture, dry roast the spices one-by-one in a heavy-based saucepan over a medium heat. Allow the spices to cool and grind all together coarsely in a pestle and mortar.
Heat the oil in a separate, heavy-based frying pan, add the garlic and cook for a couple of minutes or until golden brown. Add the ginger and onion, and stir fry over a high heat for two minutes or until the onion is softened. Add the masala spice mixture, turmeric, chilli powder and chillies and cook for a further two minutes, then add the peppers and fry over a high heat for another minute. Add the tomato purée and, still on a high heat, stir the mixture so that everything is well combined.
Add the turkey to the pan and continue to cook over a high heat for 3-4 minutes until the meat is warmed through.
Add the vinegar and sugar and season to taste with salt, stirring continuously to mix everything thoroughly together.
To serve, spoon the curry into a large serving dish. Garnish with coriander and serve with rice.