Slice the vegetables and arrange them on a baking sheet. I sliced the zucchini, squash, and peppers in halves. The onions was sliced into steaks and mushrooms were kept whole. Tip: careful not to move the onion around too much since you want to keep the slices together for easier grilling. Now Then season the top and bottom of the sliced vegetables with the seasoned oil.
Fire up the grill to medium heat (350°F-450° F).
Place the vegetables on the grill grates, close the lid and cook until tender and lightly charred. The onion, pepper, and mushroom will cook for about 8-10 minutes. The zucchini yellow squash, and asparagus will only cook for 5-6 minutes. Serve warm and enjoy!