Place the ginger and garlic in a bowl, along with the turmeric, cumin, pepper and yoghurt. Mix together, then add in the chicken pieces and mix again. Cover and refrigerate for 30 minutes.
Spray 10 squirts of frylight in a large frying pan pan (or the insert to your slow cooker if you can use it on the hob like mine. I use this [easyazon_link identifier="B00IPENZK0" locale="US" tag="kitchsanct-20"]Slow Cooker[/easyazon_link] <--affiliate link), turn the heat to high and add the marinaded chicken. Lightly brown all over (should take about 8-10 minutes) Remove the chicken and place in a bowl.
Add the onions, red peppers, chopped chillies, the stalks from the coriander (cilantro), cloves, cinnamon, cumin, coriander, paprika, salt, pepper and tomato puree to the pan. Cook for 5 mins on a medium heat, stirring regularly, until the onion starts to soften. Turn off the heat, add 4tbsp of the stock and carefully (cover if needed) whizz into a puree with a hand blender (or transfer to a food processor if you prefer).
Add the puree back into the pan, then add the chicken, remaining stock, chopped tomatoes and cardamom. Stir and bring to a simmer, then transfer to your slow cooker.
Cook on high for 3 hours or low for 5-6 hours. Alternatively, you can cover and cook on the hob for 1 ½-2 hours on a low heat, stirring regularly.
Whilst the Rogan Josh is cooking, make the onion, mint and tomato salad by mixing all of the salad ingredients together in a small bowl.
Once cooked, serve the Rogan Josh topped with a spoonful of natural yogurt, some torn/chopped fresh mint and the coriander leaves from earlier (the ones you removed the stalks from).