Hot water crust beef pie with lamb fat pastry

Cut the lamb kidney fat into chunks and render over medium-low heat, stirring occasionally, until about two cups of liquid fat, about half an hour. Strain through cheesecloth and a fine mesh sieve; discard the solids.

Bring 280 g water and 110 g rendered lamb fat to a simmer over medium heat in a small lidded saucepan. Whisk a pinch of salt into 500 g all-purpose flour.

Pour the hot fat and water over the flour and mix with a wooden spoon until no dry patches remain. Cover and rest until cool enough to handle, about 20 minutes.

Knead 5 to 7 minutes until firm but not tough. Cover in a bowl and rest at room temperature about an hour.

Break the chuck roast into bite-sized pieces, trimming sinew and connective tissue. Season with thyme, kosher salt and black pepper and scatter in onions.

Roll about a third of the dough to an 8 to 10 inch round. Shape it up around a bowl or crock used as a mold, trim the top flat, and pop the shell off the mold.

Pack the filling in as tightly as possible, since it shrinks.

Roll a smaller lid about an inch wider than the pie, brush the edges with beaten egg, lay on the lid, trim, crimp to seal, and patch weak spots.

Cut a steam vent in the center. Optionally stick four pastry leaves on top with egg wash.

Bake at 350F for 1 to 2 hours, until the pastry begins to lightly brown and the beef registers around 160F.

Brush all over with beaten egg and return to a slightly hotter oven, 375 or 400F, for 15 to 20 minutes until golden brown and burnished.

Cool 10 to 15 minutes, then move to a wire rack; ideally cool completely, about two hours.