Soil pH? Soil texture? Water pH? Abiotic/biotic stress events? So many variables. Basic chemistry-based soil analysis and petiole analysis would be good start. They aren’t expensive, even less so if it allows the veggies to be edible
I am definitely not being technical with the lingo. Best part, per my mate, was the crispy belly that he called Chicharrón, I couldn’t find any better part so I agreed. But it was all delicious, dark and light meat, skin, did not matter.
I can’t take credit, I just ate it. Mate from Brazil, that currently resides in Manson, came down and cooked one up for a harvest party. It was amazing.