At the end of her second day, company owner Randi Westphal found the till was $52.36 short - a larger variance than she had found before.
She concluded Howe-Thornley had taken a $50 note which had been in the till earlier, and sent her a text message saying: "Hi Amber, no need to come into Salad Bowl tomorrow. We'll be in touch. Thx, Randi."
Howe-Thornley thought little of the text because the new salad cart was not due to open until the following week.
But when she texted on opening day to ask what was happening, Westphal responded: "Nothing. Please return T-shirt and feel free to get another job."
Howe-Thornley asked if she would be getting paid for her two days of work, but received the response: "Money missing from till is reason you don't have a job!"
When Howe-Thornley protested she had "absolutely no idea" what she was talking about, Westphal responded: "Goodbye."
Before the authority, Westphal denied ever offering Howe-Thornley a job, saying she had asked her only to come in for a three-hour trial to see if she was suitable.
But the authority found Howe-Thornley was an employee because she had been preparing salads and serving customers.
The authority also found there was no evidence to support the allegation of theft, and the decision to dismiss Howe-Thornley was unjustified.
Judge Colgan upheld the authority's decision following an appeal to the Employment Court last July.