Combine the curry powder, allspice, sugar, chilli powder and turmeric in a small bowl. Halve the chicken thighs and place in a large bowl. Sprinkle with 2 tablespoons of the spice mix and the sea salt and turn to coat well. Reserve the remaining spice mix.
Heat the oil and butter in a large, deep frying pan or saucepan over a medium heat. Cook the chicken in batches for 1 minute each side, until golden, then transfer to a plate. Don’t let the spices catch and burn.
Add the onion, garlic, ginger, 2 sprigs thyme and the bay leaves to the pan and cook for 5 minutes, adding a splash of water if the pan is too dry. Stir in the reserved spice mix and cook for
Stir in the stock, coconut cream and soy, then add the potatoes and carrots. Bring to the boil, cover and simmer for 20 minutes.
Add the chicken, jalapeños and remaining thyme and bring back up to the boil. Reduce the heat and simmer gently for about 25 minutes with the lid slightly ajar, or until the chicken is fully cooked and the vegetables are tender. Serve with lots of hot, cooked rice or warm flatbreads.