Drain the potatoes and dry on kitchen paper. Heat the vegetable oil in a deep pan over a medium heat until hot (or heat a deep-fat fryer to 180C/350F). CAUTION: hot oil can be dangerous. Do not leave unattended. Deep-fry the potatoes in batches until crisp and golden-brown. Remove from the oil using a slotted spoon and drain on a plate lined with kitchen paper. Season with salt.
For the curry, heat the oil in a heavy-based pan or karahi over a medium heat. Add the whole spices and fry for a minute until fragrant, then add the onion and fry for 10 minutes, or until softened and golden-brown.
Stir in the tomatoes and salt and simmer for 2–3 minutes, then add the ginger, garlic, chilli powder, cumin, coriander, garam masala and turmeric and cook for a minute.
Add the chicken pieces to the pan and cook, stirring, for 2–3 minutes, or until well coated with the spice mixture, then add the jaggery, apricots, vinegar and enough water just to cover. Bring to the boil, lower the heat, cover the pan with a lid and simmer for 30–40 minutes, or until the chicken is cooked through and tender, and the sauce is reduced to a rich, thick consistency.
Serve with the potato sticks heaped on top, and scatter with coriander.