Line a large baking tray with baking parchment.
Dust a work surface with flour and roll the pastry to a 25x35cm rectangle.
Arrange three rows of overlapping chorizo slices to completely cover the pastry.
Sprinkle thinly sliced lemongrass and a twist of pepper over the chorizo.
Roll the pastry tightly into a log approximately 4cm thick.
Place the roll on the baking tray and chill in the fridge for 20 minutes.
Preheat the oven to 220°C.
Cut the firm pastry roll into 32 slices about 1cm thick.
Place slices on the tray and brush the tops with beaten egg.
Bake for 15-20 minutes until the pastry is puffed and golden-brown.