Each evening, she said, she went back to the laboratory and experimented until she deciphered the formula.
With support from a wealthy family friend, Tsang launched her own soy sauce business in 1974. Her husband fell ill, and she had to support her two boys. "It would have been quite expensive to start a canning factory," she said.
Soon her business took off and she was asked to advise various companies on setting up soy sauce factories in countries as far afield as Australia, the US and the Philippines.
Once, she turned down an invitation to head a project in Houston, Texas. Her sick husband preferred to stay in Hong Kong.
Tsang may not pass on the recipe, and seems more concerned these days in spending her evenings in the kitchen, extracting Chinese medicines from plants, fungus or insects as a hobby.
Tsang said that, although several companies wanted to learn the soy sauce method, they had no sincerity. "I am a researcher more than a businesswoman, and money is not everything."
"Thanks to the Chinese medicine, I have no health problems. I do not even need reading glasses at my age," she said, running about her spacious workshop, surrounded by Hong Kong's steep mountains.
Asked what she cooks with her soy sauce, Tsang smiled and said: "I have had no time for cooking ... [But] I am very happy."
RSS