My sensible hippie brother never throws any veggies parts unless they are bad. He boils it and makes stock for miso or soups. Man he can cook with very little waste and the food is outstanding.
Potatoes and onions: when they get old, make soup. When fish starts to stink, cook it extra long. Moldy cheese: just cut off the mold and the rest is fine. There are lots of things you don’t have to throw out.