Make a paste by grinding the chilli, ginger, garlic, the white part of the spring onion and the stems of half the bunch of coriander in a small blender (reserve the leaves for decoration at the end) - you may need to add a little water to loosen the mixture.
Heat the oil in a wok over a medium-high heat and add the chicken pieces to brown on all sides.
Stir in the paste and cook for another 1–2 minutes. Add the peanut butter, stock and yoghurt and bring the mixture to the boil. Reduce the heat and leave to simmer for 10 minutes until the chicken is fully cooked and the sauce has thickened. Add any additional greens halfway through cooking the chicken. Add the spinach leaves in the last few minutes to wilt them.
Serve with rice or noodles, garnished with chopped coriander leaves.
