This is a beef noodles from Huế - our former imperial capital! Totally different from Phở.
It's not only bún bò Huế, it's a symbolic living style from that feudal central land!
Many stories about this dish in Huế.
About how to combine the two most important meats: beef and pork, symbolizing the unique harmony as expressed in "bò nấu thì teo, heo nấu thì nở"(literally means cooked beef is shrinking, cooked pork is stretching!) or about the legendary Bà Bún (Mme Bún) who was the founder of the village named Vân Cù, near to Hương river, where the best rice noodles has been produced!
That was a part of the past!
Beef noodles in Huế style
If we compare bún bò Huế to many other dishes originated either from North or Central, bún bò Huế could be one of the first dishes appeared in Sài gòn since long! I don't know when, but should be long long ago, along with the migration waves from Central to South in early 50s of the last century!
Again just my guess!
Beef based soup but always served with pork knuckle or slices of beef shank (bò bắp)
Difficult to make a judgment where in Sài gòn serve the best bún bò Huế!
Depends on many things! Beef & pork quality. Soup quality. Noodles quality. Even chili saté quality!
And million people, million taste! Some people may prefer this or that, or it's still a habit. Used to go there! Used to eat here!