
In a medium saucepan covered with a lid, on medium heat, sweat the onion in the butter for 5 minutes until soft and cooked through. Remove the lid and continue to cook until the onion starts to caramelize, stirring occasionally for an even golden color. Add the garlic, ginger, and red chillies, cooking for 30 seconds to remove the rawness.
In a separate small frying pan on high heat, gently toast the cardamom pods, cloves, coriander seeds, cumin seeds, and black peppercorns for a minute. Remove from heat and grind to a fine powder. Add this spice mix to the onion mixture and cook for 30 seconds. Stir in the chopped tomatoes, bring to a simmer, season with sea salt, and let it reduce by a third.
Add the turkey meat, cover with a lid, and leave on low heat for at least 15 minutes. Taste and adjust the seasoning if necessary. Serve the curry with wholegrain rice, garnished with coriander and spring onions if desired. For a cooling side, mix natural yoghurt with cucumber to make a raita.