Put ¼ cup of the olive oil in the bottom of a large mixing bowl.
Smash 4 of the garlic cloves into the olive oil.
Add half of the salt and ¼ teaspoon of the pepper to the oil and stir until well combined.
Let the oil sit for about 10 minutes and stir again to let the flavors come together.
Dump all of the zucchini slices into the oil and toss around until all the slices are covered.
Then lift the slices out of the oil and lay onto a baking pan or tray. As you lift the slices out of the oil you may want to drain most of the oil from each slice.
Quickly dip each onion slice in the oil, making sure to coat both sides, then lay on the baking tray; try to keep the onion slices together as they will be easier to lay on the grill and flip if they are in one piece.
Add the remaining oil, garlic, salt and pepper to the bowl.
Then very quickly dip each piece of eggplant into the oil. Eggplant will soak up a LOT of oil, so be very quick with this step. You can also brush the oil onto the eggplant.
Heat your grill to medium-low then start by grilling the onions, they will take the most time, about 8 minutes on each side.
Then grill the zucchini and eggplant, about 4 minutes per side.
Vegetables can be served hot or at room temperature.
You can use any vegetables you like, these happen to be our family favorites.