I find a third Vietnamese restaurant in Heidelberg.

Located on Hauptstraße, Saigon Sonne (Saigon Sun) looks fanciest of the three Vietnamese restaurants that I have found in Heidelberg.  

The menu offers canh chua, three types of pho, and bun bo Hue.  

The close up for bun bo Hue looks authentic.  I'll try this dish first.  

 Frau Wuttke tells me that Dr. Henry Price has eaten at this restaurant and he likes it.