Is it the same sausage as sai krok Isan?
No. Sai ua is a northern sausage with herbs, grilled. Sai krok Isan is an Isan dish made by fermenting pork and rice, and its sour taste comes from the fermentation.
Sai Ua · ไส้อั่ว
If you fancy a fragrant meat dish in Chiang Mai, choose sai ua. It is a northern sausage of pork mixed with chilli and herbs, then grilled. A slice gives you the richness of grilled meat and the scent of herbs together. With sticky rice and vegetables it makes a good meal of northern food.

The richness of pork is joined by herb aroma and chilli seasoning. The distinctive scent is different from a familiar sausage. How hot it is depends on how it is made, so if it is your first time, you could start with a small piece.
It is a sausage of pork mixed with herbs and grilled.
Sai ua often appears on the Lanna table of the north. It is sometimes eaten with sticky rice or a dipping sauce such as nam prik. Order it with nam prik ong, which is flavoured with tomato, and vegetables, and you can alternate between the grilled meat and the sauce.
No. Sai ua is a northern sausage with herbs, grilled. Sai krok Isan is an Isan dish made by fermenting pork and rice, and its sour taste comes from the fermentation.
The standard sai ua is made with pork. If you do not eat pork, it is better to choose another dish for your meal.
If you would like to read more about the food and the regions behind it, these sources are worth a look. Ingredients and cooking methods can vary from one cook to the next.
Sharing image credit: Takeaway · CC BY-SA 3.0