How was the black pudding thickened when made from Mangaliitza pigs?

The correct answer is oats, which are traditionally used to thicken black pudding, especially in recipes involving Mangaliitza pigs. Black pudding is a type of blood sausage, and oats provide a binding texture that helps to absorb the blood and fat, resulting in a cohesive product. The use of oats not only contributes to the consistency but also adds a certain flavor profile that complements the richness of the blood and fat from the pig.

Oats have a unique ability to thicken mixtures while retaining moisture, which is key in creating that desired smooth texture in the final dish. This aspect highlights why they have become a preferred ingredient in many traditional recipes, particularly for black pudding made from specific breeds like Mangaliitza pigs, which are known for their marbled meat and rich flavor.

In contrast, the other options such as breadcrumbs, rice, and potatoes may not deliver the same binding and flavor-enhancing properties as oats do in this specific context, making oats the ideal choice for thickening black pudding.