They lived in Ms Ta's garage with one or two other employees and took all their meals with Ms Ta's family, usually at the restaurant.
Vu began working for Ms Ta in Christchurch in early 2009.
Ms Ta gave the Employment Relations Authority a notebook that she said shows evidence she paid Vu $2,280 monthly.
Member of the Authority Christine Hickey said the notebook wasn't good enough evidence to prove Vu was paid more than the $1,500 he claimed he was paid for the five years work.
After the Christchurch Earthquakes the restaurant shut down for a period and Ms Ta received subsidies to pay her staff. She didn't pay Vu any of these and Ms Hickey ordered that pay to be included in the arrears.
Ms Ta was ordered to pay Vu $150,026.99 in wage arrears, and $12,002.16 in holiday pay. He was also to be paid $327.50 gross in lost remuneration, and $8,000 in compensation.
Bao got a work visa in November 2012 and began working for Ms Ta soon after. Ms Ta didn't pay him, and Ms Hickey ordered her to pay Bao $7,041.23 in wage arrears and holiday pay. He was also to be paid $327.50 gross in lost remuneration, and $6,000 in compensation.
The Authority also found that both brothers were unjustifiably dismissed by Ms Ta on January 2, 2013.
Vu and Bao told the Authority that they were given permission to go on a fishing trip and were asked to wash and dry the tablecloths while Ms Ta was away.
They asked another employee to do the task for them, but Ms Ta returned to work earlier than expected and found the tablecloths wet. She called them and told them they no longer had a job.Ms Ta disputed this, and said she wasn't angry with them, but the authority preferred Vu and Bao's evidence.
Ms Hickey ordered Ms Ta to pay penalties that sent "an unequivocal message that breaches of minimum employment standards are totally unacceptable in New Zealand."
"There is an increasing number of cases in which vulnerable migrant workers have been subject to exploitation," she said."
This inequality is greatly increased for workers such as Vu and Bao Ho Van Nguyen, who were very vulnerable to exploitation being able to work only under work permits specifically allowing them to work for Ms Ta, who do not speak English, who were likely unaware of their rights as employees and who were bound by complex personal and family loyalty to Ms Ta despite her illegal practices.
"Ms Ta was penalised with a fine of $5,000, with $4,000 to go to Vu and $1,000 to Bao.
Costs were reserved.