Step #2 Line two 15 1/2x10 1/2-inch rimmed baking sheets with foil wrap.
Step #3 Gently toss all ingredients In a large-ish bowl until vegetables are coated with oil.
Step #4 Spread evenly on baking sheets.
Step #5 Roast 20 to 25 mins stirring once until vegetables are slightly charred & tender.
Step #6 If preparing the asparagus & onion ahead, store them in a plastic bag large enough to accommodate the rest of the ingredients so you won't have to dirty a bowl.
Enjoy the Roasted Asparagus, Mushrooms & Onions recipe