Why does a sausage taste sour?
Because it is made by fermenting pork and rice. It is a sausage enjoyed for the tang from fermentation, and how sour it actually is depends on the product and the cooking.
Sai Krok Isan · ไส้กรอกอีสาน
If you want to taste the tangy fermented foods of Isan, try sai krok Isan. It is a sausage made by fermenting pork with rice, garlic and more. The savory taste of meat is joined by the sourness that comes from fermentation. If you have tried sai ua, the Northern sausage, compare the two.

Its traits are the savory pork and the tang that comes from fermentation. The strength of the sourness depends on the degree of fermentation and the cooking. The raw chilies served with it can be hot, so eat them separately, a little at a time.
Eat the raw chilies served with it separately, a little at a time.
Sai krok Isan is an Isan dish made by fermenting pork and rice. It is not a dish eaten only in Khon Kaen. Comparing it with sai ua, the Northern sausage that celebrates herbal aroma, shows how the ingredients and flavor of sausages differ by region.
Because it is made by fermenting pork and rice. It is a sausage enjoyed for the tang from fermentation, and how sour it actually is depends on the product and the cooking.
Sai ua is a grilled Northern sausage with herbs, while sai krok Isan is an Isan sausage of fermented pork and rice. If you try both, you can compare the herbal aroma and the sourness of fermentation.
If you want to read more about the food and the regions behind it, these sources are a good place to start. Ingredients and recipes can vary from one restaurant to the next.
Sharing image credit: Takeaway · CC BY-SA 3.0