There are a couple tricks to this. One is to roast foods together that have a similar density, like root vegetables - potatoes, carrots, parsnips, etc., and cut them to a similar size, so they cook evenly.
The other is to start roasting denser vegetables first and then add less dense vegetables as time goes on. For example, start with potatoes; after 15 minutes, add onions. After another 15 minutes, add green beans. At the end of the 45 minutes, they're all done.
Anyplace where people argue about food is a good place.
~ Anthony Bourdain, Parts Unknown, 2018