Preparation

1. Start clean grill and heat to around 500 F.
2. Wash mushrooms, remove stems and peel off outer skin, if desired. Cut each mushroom into 3 pieces. Drizzle with about 1 tablespoon of the olive oil and sprinkle with a dash of salt and pepper. Toss gently and set aside.
3. Wash asparagus and trim tough ends to make 5-inch long spears. Drizzle with about a teaspoon of olive oil. Season with a dash of salt and pepper. Toss lightly and set aside.
4. Wash bell pepper, cut off top and bottom. Cut pepper from around the seeds to make 4 slabs of pepper, cut each slab lengthwise into 3 smaller strips (about 1-inch by 3 inch pieces). Drizzle with about a teaspoon of olive oil and sprinkle with a dash of salt and pepper, Toss lightly and set aside.
5. Wash zucchini (and/or yellow squash). Trim off the ends. Cut in half through the middle, then cut each half into about 4 or 5 pieces, about 1/8-inch thick. Drizzle with about 2 teaspoons of olive oil and sprinkle with salt and pepper. Toss gently and set aside.
6. Peel onion, lightly cut off the root end to get rid of the dirt and roots, but still leaving the onion in tact. Cut in half lengthwise, then set the halves on their flat side down on the cutting board. Cut each half into 3 or 4 wedges then insert a toothpick through the onion to help to hold it together. Drizzle with about 2 teaspoons of the remaining olive oil and sprinkle with a dash of salt and pepper. Toss gently and set aside.
7. Take the prepared veggies to the heated grill and carefully place the pieces on the grates in a single layer at a 90 degree angle to the grates so that the vegetables don't slip through (they are slippery - and occasionally one or two can get away). Cook for about 2-3 minutes, then turn veggies over, starting with the asparagus as it takes the least time to cook. Every grill has areas that are hotter or cooler so the cooking time for each vegetable will vary depending on their location. Total cooking time for asparagus is about 4 minutes, for the mushrooms, peppers and onions about 10 minutes, and for the zucchini about 7 minutes. As veggies are done, transfer them to a serving platter.