Fry the garlic, chilli, coriander root & ginger in a saucepan until fragrant then add the tamarind pulp and half a jar of water, bring to the boil and simmer for 5 to 10 minutes then add in the fish sauce and palm sugar.
Heat some oil and butter in two pans and season both the potatoes and fish with some salt and pepper.
Place the fish in one of the pans skin side down and cook until golden on one side then flip over and cook until just done, whilst cooking your potatoes the same way in the other pan.
Place some sauce in the middle of a plate, place your potato next, then your fish, skin side up, then a dollop of yoghurt then the chilli powder, sprig of coriander and scatter some diced cucumber onto the sauce.
Great with an Asian beer and some steamed bok choy or choy sum.