The surveillance video shows a young man attacking the 48-year-old worker in Hamburg's Eimsbüttel neighbourhood by approaching him from behind and stabbing him multiple times, causing nearly fatal wounds.
The suspect then fled along Schwenkestraße, a nearby side street, while the worker was brought to the hospital in critical condition, according to the police report.
The February 13 attack was likely linked to an incident the night before when two young men, accompanied by two young women, argued with the shopkeeper over the quality of their döner meat.
Police suspect that one of the two men returned the next day to commit the assault.
The suspect is believed to be 20- to 25-years-old, between 175 and 180 centimetres tall, and was wearing jeans and a dark hooded jacket at the scene of the crime.
The homicide division of Hamburg's state police has taken over the investigation.
Witnesses with further information have been asked to call the bureau at 040/4286-56789.