1. Preheat oven to 450°F.
2. Break off ends of asparagus then cut spears in 2-inch pieces.
3. Slice zucchini and yellow squash into ½” slices then cut slices in half.
4. Peel red onions then cut into quarters, keeping root end intact.
5. Peel garlic cloves.
6. Combine vegetables in large roasting pan or rimmed cookie sheet lined with foil.
7. Drizzle with 2 tablespoons olive oil. Sprinkle with salt and freshly ground black pepper, and toss to coat thoroughly.
8. Place roasting pan in oven. Roast until vegetables are just tender and slightly browned, about 30 minutes, stirring once or twice during roasting.
