A few people, not just this man have made instruments out of vegetables. They use existing instruments as a basis for their new unique instruments, good designing, seeing what is successful in existing things/ remaking/re-doing using different media to see what works best.
There is a band called the Wyld Men that perform to audiences using their fruit and veg instruments.
“For the Wyld Men, it all started with the carrot flute. Later, after I had already branched out into all kinds of vegetables, I came across references to the First Vienna Vegetable Orchestra and then Flute n Veg”
People who make vegetable instruments have to be experimental to find which vegetable would be best to make each instrument out of as “different vegetables have different scales and are therefore suited to different melodies: a sweet potato makes an ocarina, a bamboo shoot becomes a flute, a yam, a whistle.”
This is true of any material/medium within most practices. Experimentation is a key part of any design process.
The Vegetable Orchestra is another group who play vegetable instruments.