Make dressing in a small bowl and keep aside.
Take a large bowl and add all the vegetables in it. Pour the dressing. Mix it well with a fork or hands.
Marinade for 2-3 hrs.
Take 4-5 bamboo skewers. Wet them in water. Start skewering the Vegetables on the bamboo skewers in a pattern - mushroom, bell pepper, onion, bell pepper, mushroom and so on. You can make it a long skewer or a short skewer, depending upon how big is your grill.
Grill on electric grill or flat griddle / tawa or on the backyard grill. Keep rotating the skewers for even grilling. Grill till you see slight charred marks on the vegetables. Since these are vegetables, it does not take long to grill the skewers.
Serve with ranch or dip of your choice.
You can also serve it with some pita, naan, rice or pasta on the side.