CUT VEGETABLES: Slice the vegetables into serving pieces. Peppers and zucchini lengthwise; onions and eggplant in round disks; break the ends off asparagus stalks.
SEASON AND GRILL VEGETABLES: Lay the vegetables on a foil lined pan. Brush or drizzle them lightly with olive oil (I love using Catalina or French salad dressing instead). Sprinkle with salt, pepper and fresh or dried oregano (or thyme). Flip over the vegetables and repeat.
GRILL VEGETABLES on each side for a couple of minutes just until tender and grill marks appear. Sprinkle lightly with balsamic vinegar if desired or drizzle with balsamic reduction. Serve warm or at room temperature.
Notes
Make Ahead: Grilled vegetables can be made several hours ahead and left on the counter at room temperature until serving time. If preferred, you can rewarm them for 40 seconds in the microwave or for 5-7 minutes in a 350F oven.