Place in a basin 500 g (1 lb 2 oz) pork kidney fat cut in large dice and half melted, 4 dl (14 fl oz or 1¾ U.S. cups) pig’s blood, 1 dl (3½ fl oz or ½ U.S. cup) cream, 200 g (7 oz) chopped onion cooked in lard without colour, 20 g (⅔ oz) salt, a good pinch of pepper and a pinch of mixed spice. Mix these ingredients well together, then place into the prepared gut without overfilling it; this mixture tends to swell during the cooking process and this will prevent the puddings bursting. Tie off with string at the required lengths and arrange them on a grill or lattice wicker frame.
Plunge the whole into a pot of boiling water, reheat to 95 °C but no hotter and poach the puddings at this temperature for 20 minutes. Prick any which float to the surface with a pin so as to release the air which they contain; this will prevent them from bursting.
When cooked, remove from the water and allow them to cool on the frame.
To serve; make shallow incisions on both sides of the puddings and grill very gently. Serve accompanied with a dish of creamed mashed potato.