While fish is relatively quickly done, vegetables can take from 5 to 20 minutes to cook on the grill. Remove them as they become tender and place them on a covered dish to help retain heat and moisture. Avoid moving your veggies pieces too much or they will steam rather than grill. If you are cooking veggies with meat, place the vegetables around the side of the grill crate so they are not directly over the coals which will flare up when the meat drips on them.
(Photo courtesy of Williams-Sonoma)