This recipe is a clever little twist. As massaman curry usually contains chunks of potato we thought why not have the potato on top in pie form? The result - a beautiful marriage between two disparate but delicious classics.
Preheat the oven to 150°C.
In a frying pan (or a cast iron casserole) add the oil and the beef, frying hard until nicely browned. Season on both sides and remove the beef.
Pour half the coconut milk into the pan along with the curry paste. Cook until the mixture looks like it's going to split, being careful it doesn't burn by constant stirring.
Pour in the rest of the coconut milk, along with the sugar, fish sauce, cinnamon, lime leaves, onion, water or chicken stock and the tamarind, stirring to combine it all together. Return the beef pieces, making sure they are completely submerged. Place a lid tightly on top and place in the oven until the beef is tender - roughly 2 hours.
When tender, remove the bones. Remove the meat and reduce the liquid until it's evaporated by at least half. Skim some of the fat from the surface of the curry. Add the meat back in and spoon the curry into a deep pie dish.
Boil the potatoes until tender and pass them through a ricer. Fold through the curry fat and salt, then when the mixture has cooled mix through the egg. Spread this over the curry, or pipe it on if you are feeling fancy.
Crank up the oven to 180°C and bake for around 30 minutes, or until the filling is bubbling the mash crisp on top.
Serve!