Slice the chicken thighs into 5cm strips approximately 7-10mm in profile.
Add the cumin, coriander, and salt to the chicken, then mix and allow to sit whilst you prepare the remaining ingredients.
Cut the onion in half, peel it, then slice it into half-moon shapes 5mm (¼") thick.
Peel the garlic and ginger and pound in a pestle and mortar to form a paste.
Cut the green chilli peppers in half lengthways.
Cut the tomato into 8 wedges, then cut out the seeds and discard them. Cut the remaining flesh into a 5-7mm dice.
Heat the oil in a wok over a medium-high heat. When it's hot, add the dried chillies along with the mustard, cumin, pomegranate, fennel and fenugreek seeds.
As soon as the seeds begin to crackle, add the curry leaves and onion, then cook for 5 minutes
Add the chicken, reduce the heat to medium, stir well, then cook for 5 minutes, stirring a couple of times.
Add the garlic and ginger paste, tomato paste, green chillies and tomato flesh, stir and cook for 2 minutes.
Pour in the vinegar, water and add the jaggery, then stir well and cook on low-medium for 10 minutes.
Roughly chop the coriander and stir it through the chicken just before serving.
Video
Notes
I like to use mustard oil for this dish; however, it is generally marked as "for external use only" in the UK, US and the EU, due to the levels of euric acid.I only use it in a few dishes, and they are dishes that I don't eat often, but it adds an incredible flavour to some curries, this one being a perfect example.If you are using mustard oil, you need to heat it to the smoking point first and then cool it a little before starting.