Put the onion, tomato purée, cashew nuts, garam masala, garlic, lemon juice, turmeric, salt and yogurt into a food processor or blender and process until fairly smooth. Set aside.
Heat the oil in a large, nonstick frying pan. When hot, pour in the spice mixture. Fry, stirring, for 2 minutes over a medium heat.
Add half the chopped coriander, the apricots and chicken to the pan and stir-fry for 1 minute.
Pour in the chicken stock, cover and simmer for 10–12 minutes or until the chicken is cooked through and tender.
Stir in the remaining chopped coriander and serve with steamed rice and pappadom.