The idea of making a kind of sausage using congealed pigs blood is one that is fairly widespread throughout the world. The French have their boudin noir, the Spanish their morcilla and the Brits their black pudding, or blood pudding.
Prep the Ingredients
The oats need to be soaked in cold water for about 30 minutes. Cut the pork fat into tiny cubes, about 5mm (a quarter of an inch). Peel and chop the onion into similarly sized pieces. Hydrate the blood by mixing 1 part powdered blood with 6-7 parts cold water. Make up your spice/seasoning mix in a small glass jar.
Make the Black Pudding
Drain the oats and add them to the blood in a large bowl. Add all the other ingredients and stir well.
Tray-Baked Black Pudding
This is usually seen made by artisan producers and traditional butchers. Pre-heat your oven to 150°C (302°F) if it's a fan oven, 170°C (338°F) if not. Pour the mixture into an ovenproof dish. Cut a piece of aluminium foil large enough to cover the dish. Oil one side of the foil, and wrap it tightly over the dish. Place the dish inside another, larger ovenproof container, and fill the gap between the two with boiling water to form a bain marie. Put the bain marie in the oven and bake it for 1 hour - 90 minutes until the pudding is firm to the touch.
Black Pudding Sausages
Commercial black puddings are usually about 7cm / 3 inches diameter and made in a plastic casing - you can usually get these wherever you get your dried blood from. But you also see smaller sausages about the size of a normal pork sausage. With a big casing, close off one end, spoon the mixture in and close the open end. With smaller casings, tie a knot in one end and thread the casing onto a funnel. You can't really use a sausage stuffer for this because the mixture is too runny and the cubes of fat would be destroyed and gunk up your mincer/stuffer. So, spoon the mixture into the funnel and shove it down with the end of a wooden spoon or a skewer if it gets stuck. Tie off the open end, and divide into links by twisting the casing or by tying with string.
The sausages need to be cooked in hot water at 77°C (170°F) for 30-45 minutes until they are firm to the touch. A sous-vide device is ideal for this, but you'd be wise to put your sausages in a sealed bag in case they burst.
Serve the Black Pudding
Although the black pudding is cooked already, it's best to finish it off by fairly brief cooking in a frying pan - don't fry it too much.