First make the curry paste by pounding the ingredients together in a mortar and pestle, or, if you're short on time, blitzing them in a blender.
Cut the chicken leg into two through the thigh joint. If the pieces are large, cut each one in half again.
Marinate the chicken in the fish sauce for an hour and then mix in the curry paste and leave for a few hours.
Heat fresh coconut cream and then add marinated chicken and simmer gently along with most of the dried spices and turmeric.
When almost cooked (ours took around 40 minutes) add the shallots and simmer, seasoning with palm sugar and fish sauce. Simmer until it becomes quite oily and add extra coconut cream as required.
Add the chicken stock and simmer until the chicken is cooked. When the chicken is cooked add the potatoes, the pandanus and toasted cassia bark.
Check the seasoning. It should be rich, salty and lightly spiced.
With the seasoning correct, leave for 20 minutes in a warm place to let the spices ‘ripen’.
Reheat and check the seasoning. Adjust as necessary to taste.
Finish with a squeeze of mandarin, if using.
Serve with steamed jasmine rice and Thai cucumber relish.