Gran Kalvinder Mander hit a customer with the weapon as he grappled with the owner in a Leeds takeaway.
The dispute at Yorks Road Fisheries started when the punter complained about the colour of his vinegar.
After his complaint was ignored, the customer, who has not been named, refused to pay for his chip butty.
He was given back his money but refused to leave without his carb-laden sandwich.
“I have been treated like this because of a bit of vinegar”
Mander’s husband went from behind the counter and tried to stop him leaving with the food.
Prosecutor Andrew Horton told Leeds Crown Court Mander picked up a knife but did not threaten him with it.
Mr Horton said Mander hit him with her fist while holding the knife.
All three then calmed down and the customer could be seen on camera handing Mander her white chef’s hat back.
The customer was scratched during the struggle and his necklace was broken.
In a statement made after the incident, the customer said: “I have been treated like this because of a bit of vinegar.”
Mitigating, Shufquat Khan said Mander had acted out of instinct to protect her husband from a “younger fitter man”.
He added : “It created a very dangerous situation. But it was short-lived and thankfully he was not hurt.”
The incident escalated over the colour of the vinegar.
“It is the same vinegar that has been served in the shop for the last 17 years without complaint,” he added.
Judge Christopher Batty said: “You did not point the blade of the knife at him.
“It was a wholly unusual set of circumstances where you acted very inappropriately but in the heat of the moment.
“In all of those circumstances it would be very unjust to send you to custody.”
Mander, 52, pleaded guilty to threatening a person with a blade in a public place in relation to the incident on December 19 last year.
Mander was ordered to do 100 hours of unpaid work and pay £300 court costs.