Just in front of St. Peter and Paul Church, MySapa is a really good vietnamese and asian restaurant.
They have plenty of options to choose from, but certainly I just sticked to eating the Yellow Curry Duck dish, which for me was really good. Specially if the duck was really crispy.
The prices at the restaurant are good, ranging from 8 Euros to 16 Euros.
Asian food is always a good option, and MySapa is one to visit in Heilbronn.