This is the red fermented beancurd (nam yue) which is not commonly used except for a few dishes because of its strong smell and taste. Some of the dishes I cooked using this ingredient are:
1) Loh Han Chai
2) Braised yam and 3-layer pork
3) Stew lamb (with dong guai)
4) Fried chicken
It is to be used sparingly beause it is very, very salty.
There is another type of white fermented beancurd (fu yi), usually with chili oil, which can be eaten with white porridge. This red one is NOT for eating with porridge.
Actually, all these preserved foods are not recommended to be consumed often because it has been suspected that most Chinese who contracted nose cancer because of them. True or not, I am not sure.